diff --git a/src/builtin.cpp b/src/builtin.cpp
index 7efd57e3b..e9018a833 100644
--- a/src/builtin.cpp
+++ b/src/builtin.cpp
@@ -452,7 +452,6 @@ static int builtin_bind(parser_t &parser, io_streams_t &streams, wchar_t **argv)
     while (1) {
         int opt_index = 0;
         int opt = w.wgetopt_long_only(argc, argv, L"aehkKfM:m:", long_options, &opt_index);
-
         if (opt == -1) break;
 
         switch (opt) {
@@ -501,6 +500,10 @@ static int builtin_bind(parser_t &parser, io_streams_t &streams, wchar_t **argv)
                 builtin_unknown_option(parser, streams, argv[0], argv[w.woptind - 1]);
                 return STATUS_BUILTIN_ERROR;
             }
+            default: {
+                DIE("unexpected opt");
+                break;
+            }
         }
     }
 
@@ -625,6 +628,10 @@ static int builtin_block(parser_t &parser, io_streams_t &streams, wchar_t **argv
                 builtin_unknown_option(parser, streams, argv[0], argv[w.woptind - 1]);
                 return STATUS_BUILTIN_ERROR;
             }
+            default: {
+                DIE("unexpected opt");
+                break;
+            }
         }
     }
 
@@ -665,6 +672,10 @@ static int builtin_block(parser_t &parser, io_streams_t &streams, wchar_t **argv
                     block = parser.block_at_index(++block_idx);
                 }
             }
+            default: {
+                DIE("unexpected scope");
+                break;
+            }
         }
         if (block) {
             block->event_blocks.push_front(eb);
@@ -713,6 +724,10 @@ static int builtin_builtin(parser_t &parser, io_streams_t &streams, wchar_t **ar
                 builtin_unknown_option(parser, streams, argv[0], argv[w.woptind - 1]);
                 return STATUS_BUILTIN_ERROR;
             }
+            default: {
+                DIE("unexpected opt");
+                break;
+            }
         }
     }
 
@@ -759,6 +774,10 @@ static int builtin_emit(parser_t &parser, io_streams_t &streams, wchar_t **argv)
                 builtin_unknown_option(parser, streams, argv[0], argv[w.woptind - 1]);
                 return STATUS_BUILTIN_ERROR;
             }
+            default: {
+                DIE("unexpected opt");
+                break;
+            }
         }
     }
 
@@ -812,6 +831,10 @@ static int builtin_command(parser_t &parser, io_streams_t &streams, wchar_t **ar
                 builtin_unknown_option(parser, streams, argv[0], argv[w.woptind - 1]);
                 return STATUS_BUILTIN_ERROR;
             }
+            default: {
+                DIE("unexpected opt");
+                break;
+            }
         }
     }
 
@@ -870,6 +893,10 @@ static int builtin_generic(parser_t &parser, io_streams_t &streams, wchar_t **ar
                 builtin_unknown_option(parser, streams, argv[0], argv[w.woptind - 1]);
                 return STATUS_BUILTIN_ERROR;
             }
+            default: {
+                DIE("unexpected opt");
+                break;
+            }
         }
     }
 
@@ -934,6 +961,7 @@ static wcstring functions_def(const wcstring &name) {
                 append_format(out, L" --on-event %ls", next->str_param1.c_str());
                 break;
             }
+            default: { DIE("unexpected next->type"); }
         }
     }
 
@@ -1048,6 +1076,10 @@ static int builtin_functions(parser_t &parser, io_streams_t &streams, wchar_t **
                 builtin_unknown_option(parser, streams, argv[0], argv[w.woptind - 1]);
                 return STATUS_BUILTIN_ERROR;
             }
+            default: {
+                DIE("unexpected opt");
+                break;
+            }
         }
     }
 
@@ -1193,9 +1225,11 @@ static unsigned int builtin_echo_digit(wchar_t wc, unsigned int base) {
         case L'7': {
             return 7;
         }
+        default: { break; }
     }
 
-    if (base == 16) switch (wc) {
+    if (base == 16) {
+        switch (wc) {
             case L'8': {
                 return 8;
             }
@@ -1226,7 +1260,10 @@ static unsigned int builtin_echo_digit(wchar_t wc, unsigned int base) {
             case L'F': {
                 return 15;
             }
+            default: { break; }
         }
+    }
+
     return UINT_MAX;
 }
 
@@ -1642,6 +1679,10 @@ int builtin_function(parser_t &parser, io_streams_t &streams, const wcstring_lis
                 res = 1;
                 break;
             }
+            default: {
+                DIE("unexpected opt");
+                break;
+            }
         }
     }
 
@@ -1760,6 +1801,10 @@ static int builtin_random(parser_t &parser, io_streams_t &streams, wchar_t **arg
                 builtin_unknown_option(parser, streams, argv[0], argv[w.woptind - 1]);
                 return STATUS_BUILTIN_ERROR;
             }
+            default: {
+                DIE("unexpected opt");
+                break;
+            }
         }
     }
 
@@ -1915,6 +1960,10 @@ static int builtin_read(parser_t &parser, io_streams_t &streams, wchar_t **argv)
                 builtin_unknown_option(parser, streams, argv[0], argv[w.woptind - 1]);
                 return STATUS_BUILTIN_ERROR;
             }
+            default: {
+                DIE("unexpected opt");
+                break;
+            }
         }
     }
 
@@ -2125,7 +2174,6 @@ static int builtin_status(parser_t &parser, io_streams_t &streams, wchar_t **arg
     };
 
     int mode = NORMAL;
-
     int argc = builtin_count_args(argv);
     int res = STATUS_BUILTIN_OK;
 
@@ -2213,11 +2261,18 @@ static int builtin_status(parser_t &parser, io_streams_t &streams, wchar_t **arg
                 builtin_unknown_option(parser, streams, argv[0], argv[w.woptind - 1]);
                 return STATUS_BUILTIN_ERROR;
             }
+            default: {
+                DIE("unexpected opt");
+                break;
+            }
         }
     }
 
     if (!res) {
         switch (mode) {
+            case DONE: {
+                break;
+            }
             case CURRENT_FILENAME: {
                 const wchar_t *fn = parser.current_filename();
 
@@ -2270,6 +2325,7 @@ static int builtin_status(parser_t &parser, io_streams_t &streams, wchar_t **arg
                 streams.out.append(parser.stack_trace());
                 break;
             }
+            default: { break; }
         }
     }
 
@@ -2426,6 +2482,10 @@ static int builtin_contains(parser_t &parser, io_streams_t &streams, wchar_t **a
                 should_output_index = true;
                 break;
             }
+            default: {
+                DIE("unexpected opt");
+                break;
+            }
         }
     }
 
diff --git a/src/builtin_commandline.cpp b/src/builtin_commandline.cpp
index 1836b2377..9941a62cc 100644
--- a/src/builtin_commandline.cpp
+++ b/src/builtin_commandline.cpp
@@ -127,6 +127,10 @@ static void replace_part(const wchar_t *begin, const wchar_t *end, const wchar_t
             out_pos += wcslen(insert);
             break;
         }
+        default: {
+            DIE("unexpected append_mode");
+            break;
+        }
     }
     out.append(end);
     reader_set_buffer(out, out_pos);
@@ -326,6 +330,10 @@ int builtin_commandline(parser_t &parser, io_streams_t &streams, wchar_t **argv)
                 builtin_unknown_option(parser, streams, argv[0], argv[w.woptind - 1]);
                 return 1;
             }
+            default: {
+                DIE("unexpected opt");
+                break;
+            }
         }
     }
 
@@ -470,6 +478,10 @@ int builtin_commandline(parser_t &parser, io_streams_t &streams, wchar_t **argv)
             parse_util_token_extent(get_buffer(), get_cursor_pos(), &begin, &end, 0, 0);
             break;
         }
+        default: {
+            DIE("unexpected buffer_part");
+            break;
+        }
     }
 
     int arg_count = argc - w.woptind;
diff --git a/src/builtin_complete.cpp b/src/builtin_complete.cpp
index ec14f8ffe..489ff3c91 100644
--- a/src/builtin_complete.cpp
+++ b/src/builtin_complete.cpp
@@ -283,6 +283,10 @@ int builtin_complete(parser_t &parser, io_streams_t &streams, wchar_t **argv) {
                 res = true;
                 break;
             }
+            default: {
+                DIE("unexpected opt");
+                break;
+            }
         }
     }
 
diff --git a/src/builtin_jobs.cpp b/src/builtin_jobs.cpp
index 72765cb82..7a92e6b9e 100644
--- a/src/builtin_jobs.cpp
+++ b/src/builtin_jobs.cpp
@@ -101,6 +101,10 @@ static void builtin_jobs_print(const job_t *j, int mode, int header, io_streams_
             }
             break;
         }
+        default: {
+            DIE("unexpected mode");
+            break;
+        }
     }
 }
 
@@ -159,6 +163,10 @@ int builtin_jobs(parser_t &parser, io_streams_t &streams, wchar_t **argv) {
                 builtin_unknown_option(parser, streams, argv[0], argv[w.woptind - 1]);
                 return 1;
             }
+            default: {
+                DIE("unexpected opt");
+                break;
+            }
         }
     }
 
diff --git a/src/builtin_printf.cpp b/src/builtin_printf.cpp
index 7442673fe..d43927250 100644
--- a/src/builtin_printf.cpp
+++ b/src/builtin_printf.cpp
@@ -541,6 +541,12 @@ void builtin_printf_state_t::print_direc(const wchar_t *start, size_t length, wc
             }
             break;
         }
+        default: {
+            // TODO: Determine if this should call DIE()
+            // WTF
+            DIE("unexpected opt");
+            break;
+        }
     }
 }
 
diff --git a/src/builtin_set.cpp b/src/builtin_set.cpp
index 0427427ec..643a08bd0 100644
--- a/src/builtin_set.cpp
+++ b/src/builtin_set.cpp
@@ -123,6 +123,9 @@ static int my_env_set(const wchar_t *key, const wcstring_list_t &val, int scope,
     }
 
     switch (env_set(key, val_str, scope | ENV_USER)) {
+        case ENV_OK: {
+            break;
+        }
         case ENV_PERM: {
             streams.err.append_format(_(L"%ls: Tried to change the read-only variable '%ls'\n"),
                                       L"set", key);
@@ -143,6 +146,10 @@ static int my_env_set(const wchar_t *key, const wcstring_list_t &val, int scope,
             retcode = 1;
             break;
         }
+        default: {
+            DIE("unexpected env_set() ret val");
+            break;
+        }
     }
 
     return retcode;
diff --git a/src/builtin_set_color.cpp b/src/builtin_set_color.cpp
index b12c39229..b05bf016d 100644
--- a/src/builtin_set_color.cpp
+++ b/src/builtin_set_color.cpp
@@ -77,13 +77,13 @@ int builtin_set_color(parser_t &parser, io_streams_t &streams, wchar_t **argv) {
     // Parse options to obtain the requested operation and the modifiers.
     w.woptind = 0;
     while (1) {
-        int c = w.wgetopt_long(argc, argv, short_options, long_options, 0);
+        int opt = w.wgetopt_long(argc, argv, short_options, long_options, 0);
 
-        if (c == -1) {
+        if (opt == -1) {
             break;
         }
 
-        switch (c) {
+        switch (opt) {
             case 0: {
                 break;
             }
@@ -110,6 +110,10 @@ int builtin_set_color(parser_t &parser, io_streams_t &streams, wchar_t **argv) {
             case '?': {
                 return STATUS_BUILTIN_ERROR;
             }
+            default: {
+                DIE("unexpected opt");
+                break;
+            }
         }
     }
 
diff --git a/src/builtin_string.cpp b/src/builtin_string.cpp
index 0f01096df..eb8e7e2f1 100644
--- a/src/builtin_string.cpp
+++ b/src/builtin_string.cpp
@@ -100,12 +100,13 @@ static int string_escape(parser_t &parser, io_streams_t &streams, int argc, wcha
     escape_flags_t flags = ESCAPE_ALL;
     wgetopter_t w;
     for (;;) {
-        int c = w.wgetopt_long(argc, argv, short_options, long_options, 0);
+        int opt = w.wgetopt_long(argc, argv, short_options, long_options, 0);
 
-        if (c == -1) {
+        if (opt == -1) {
             break;
         }
-        switch (c) {
+
+        switch (opt) {
             case 0: {
                 break;
             }
@@ -117,6 +118,10 @@ static int string_escape(parser_t &parser, io_streams_t &streams, int argc, wcha
                 string_unknown_option(parser, streams, argv[0], argv[w.woptind - 1]);
                 return BUILTIN_STRING_ERROR;
             }
+            default: {
+                DIE("unexpected opt");
+                break;
+            }
         }
     }
 
@@ -145,11 +150,13 @@ static int string_join(parser_t &parser, io_streams_t &streams, int argc, wchar_
     bool quiet = false;
     wgetopter_t w;
     for (;;) {
-        int c = w.wgetopt_long(argc, argv, short_options, long_options, 0);
-        if (c == -1) {
+        int opt = w.wgetopt_long(argc, argv, short_options, long_options, 0);
+
+        if (opt == -1) {
             break;
         }
-        switch (c) {
+
+        switch (opt) {
             case 0: {
                 break;
             }
@@ -161,6 +168,10 @@ static int string_join(parser_t &parser, io_streams_t &streams, int argc, wchar_
                 string_unknown_option(parser, streams, argv[0], argv[w.woptind - 1]);
                 return BUILTIN_STRING_ERROR;
             }
+            default: {
+                DIE("unexpected opt");
+                break;
+            }
         }
     }
 
@@ -202,12 +213,12 @@ static int string_length(parser_t &parser, io_streams_t &streams, int argc, wcha
     bool quiet = false;
     wgetopter_t w;
     for (;;) {
-        int c = w.wgetopt_long(argc, argv, short_options, long_options, 0);
+        int opt = w.wgetopt_long(argc, argv, short_options, long_options, 0);
 
-        if (c == -1) {
+        if (opt == -1) {
             break;
         }
-        switch (c) {
+        switch (opt) {
             case 0: {
                 break;
             }
@@ -219,6 +230,10 @@ static int string_length(parser_t &parser, io_streams_t &streams, int argc, wcha
                 string_unknown_option(parser, streams, argv[0], argv[w.woptind - 1]);
                 return BUILTIN_STRING_ERROR;
             }
+            default: {
+                DIE("unexpected opt");
+                break;
+            }
         }
     }
 
@@ -499,12 +514,12 @@ static int string_match(parser_t &parser, io_streams_t &streams, int argc, wchar
     bool regex = false;
     wgetopter_t w;
     for (;;) {
-        int c = w.wgetopt_long(argc, argv, short_options, long_options, 0);
+        int opt = w.wgetopt_long(argc, argv, short_options, long_options, 0);
 
-        if (c == -1) {
+        if (opt == -1) {
             break;
         }
-        switch (c) {
+        switch (opt) {
             case 0: {
                 break;
             }
@@ -536,6 +551,10 @@ static int string_match(parser_t &parser, io_streams_t &streams, int argc, wchar
                 string_unknown_option(parser, streams, argv[0], argv[w.woptind - 1]);
                 return BUILTIN_STRING_ERROR;
             }
+            default: {
+                DIE("unexpected opt");
+                break;
+            }
         }
     }
 
@@ -731,12 +750,12 @@ static int string_replace(parser_t &parser, io_streams_t &streams, int argc, wch
     bool regex = false;
     wgetopter_t w;
     for (;;) {
-        int c = w.wgetopt_long(argc, argv, short_options, long_options, 0);
+        int opt = w.wgetopt_long(argc, argv, short_options, long_options, 0);
 
-        if (c == -1) {
+        if (opt == -1) {
             break;
         }
-        switch (c) {
+        switch (opt) {
             case 0: {
                 break;
             }
@@ -760,6 +779,10 @@ static int string_replace(parser_t &parser, io_streams_t &streams, int argc, wch
                 string_unknown_option(parser, streams, argv[0], argv[w.woptind - 1]);
                 return BUILTIN_STRING_ERROR;
             }
+            default: {
+                DIE("unexpected opt");
+                break;
+            }
         }
     }
 
@@ -876,6 +899,10 @@ static int string_split(parser_t &parser, io_streams_t &streams, int argc, wchar
                 string_unknown_option(parser, streams, argv[0], argv[w.woptind - 1]);
                 return BUILTIN_STRING_ERROR;
             }
+            default: {
+                DIE("unexpected opt");
+                break;
+            }
         }
     }
 
@@ -989,6 +1016,10 @@ static int string_sub(parser_t &parser, io_streams_t &streams, int argc, wchar_t
                 string_unknown_option(parser, streams, argv[0], argv[w.woptind - 1]);
                 return BUILTIN_STRING_ERROR;
             }
+            default: {
+                DIE("unexpected opt");
+                break;
+            }
         }
     }
 
@@ -1078,6 +1109,10 @@ static int string_trim(parser_t &parser, io_streams_t &streams, int argc, wchar_
                 string_unknown_option(parser, streams, argv[0], argv[w.woptind - 1]);
                 return BUILTIN_STRING_ERROR;
             }
+            default: {
+                DIE("unexpected opt");
+                break;
+            }
         }
     }
 
diff --git a/src/builtin_ulimit.cpp b/src/builtin_ulimit.cpp
index 6c67eb9f1..5cc752982 100644
--- a/src/builtin_ulimit.cpp
+++ b/src/builtin_ulimit.cpp
@@ -262,6 +262,10 @@ int builtin_ulimit(parser_t &parser, io_streams_t &streams, wchar_t **argv) {
                 builtin_unknown_option(parser, streams, argv[0], argv[w.woptind - 1]);
                 return 1;
             }
+            default: {
+                DIE("unexpected opt");
+                break;
+            }
         }
     }
 
diff --git a/src/common.cpp b/src/common.cpp
index d5bd5ee38..0fa22b310 100644
--- a/src/common.cpp
+++ b/src/common.cpp
@@ -1220,6 +1220,7 @@ static bool unescape_string_internal(const wchar_t *const input, const size_t in
                     to_append_or_none = unescape_special ? INTERNAL_SEPARATOR : NOT_A_WCHAR;
                     break;
                 }
+                default: { break; }
             }
         } else if (mode == mode_single_quotes) {
             if (c == L'\\') {
@@ -1297,6 +1298,7 @@ static bool unescape_string_internal(const wchar_t *const input, const size_t in
                     }
                     break;
                 }
+                default: { break; }
             }
         }
 
diff --git a/src/common.h b/src/common.h
index 3afae7a6c..33781f680 100644
--- a/src/common.h
+++ b/src/common.h
@@ -211,6 +211,9 @@ extern bool has_working_tty_timestamps;
     }
 
 /// Pause for input, then exit the program. If supported, print a backtrace first.
+// The `return` will never be run  but silences oclint warnings. Especially when this is called
+// from within a `switch` block. As of the time I'm writing this oclint doesn't recognize the
+// `__attribute__((noreturn))` on the exit_without_destructors() function.
 #define FATAL_EXIT()                        \
     {                                       \
         char exit_read_buff;                \
diff --git a/src/env.cpp b/src/env.cpp
index 75784624c..2ac7fe2ba 100644
--- a/src/env.cpp
+++ b/src/env.cpp
@@ -476,6 +476,25 @@ static env_node_t *env_get_node(const wcstring &key) {
     return env;
 }
 
+/// Set the value of the environment variable whose name matches key to val.
+///
+/// Memory policy: All keys and values are copied, the parameters can and should be freed by the
+/// caller afterwards
+///
+/// \param key The key
+/// \param val The value
+/// \param mode The type of the variable. Can be any combination of ENV_GLOBAL, ENV_LOCAL,
+/// ENV_EXPORT and ENV_USER. If mode is zero, the current variable space is searched and the current
+/// mode is used. If no current variable with the same name is found, ENV_LOCAL is assumed.
+///
+/// Returns:
+///
+/// * ENV_OK on success.
+/// * ENV_PERM, can only be returned when setting as a user, e.g. ENV_USER is set. This means that
+/// the user tried to change a read-only variable.
+/// * ENV_SCOPE, the variable cannot be set in the given scope. This applies to readonly/electric
+/// variables set from the local or universal scopes, or set as exported.
+/// * ENV_INVALID, the variable value was invalid. This applies only to special variables.
 int env_set(const wcstring &key, const wchar_t *val, env_mode_flags_t var_mode) {
     ASSERT_IS_MAIN_THREAD();
     bool has_changed_old = has_changed_exported;
@@ -512,7 +531,7 @@ int env_set(const wcstring &key, const wchar_t *val, env_mode_flags_t var_mode)
                 umask(mask);
                 // Do not actually create a umask variable, on env_get, it will be calculated
                 // dynamically.
-                return 0;
+                return ENV_OK;
             }
         }
 
@@ -636,7 +655,7 @@ int env_set(const wcstring &key, const wchar_t *val, env_mode_flags_t var_mode)
     // debug( 1, L"env_set: return from event firing" );
 
     react_to_variable_change(key);
-    return 0;
+    return ENV_OK;
 }
 
 /// Attempt to remove/free the specified key/value pair from the specified map.
diff --git a/src/env.h b/src/env.h
index 6f783312c..56a84ffde 100644
--- a/src/env.h
+++ b/src/env.h
@@ -36,8 +36,8 @@ enum {
 };
 typedef uint32_t env_mode_flags_t;
 
-/// Error code for trying to alter read-only variable.
-enum { ENV_PERM = 1, ENV_SCOPE, ENV_INVALID };
+/// Return values for `env_set()`.
+enum { ENV_OK, ENV_PERM, ENV_SCOPE, ENV_INVALID };
 
 /// A struct of configuration directories, determined in main() that fish will optionally pass to
 /// env_init.
@@ -51,26 +51,6 @@ struct config_paths_t {
 /// Initialize environment variable data.
 void env_init(const struct config_paths_t *paths = NULL);
 
-/// Set the value of the environment variable whose name matches key to val.
-///
-/// Memory policy: All keys and values are copied, the parameters can and should be freed by the
-/// caller afterwards
-///
-/// \param key The key
-/// \param val The value
-/// \param mode The type of the variable. Can be any combination of ENV_GLOBAL, ENV_LOCAL,
-/// ENV_EXPORT and ENV_USER. If mode is zero, the current variable space is searched and the current
-/// mode is used. If no current variable with the same name is found, ENV_LOCAL is assumed.
-///
-/// \returns 0 on success or an error code on failiure.
-///
-/// The current error codes are:
-///
-/// * ENV_PERM, can only be returned when setting as a user, e.g. ENV_USER is set. This means that
-/// the user tried to change a read-only variable.
-/// * ENV_SCOPE, the variable cannot be set in the given scope. This applies to readonly/electric
-/// variables set from the local or universal scopes, or set as exported.
-/// * ENV_INVALID, the variable value was invalid. This applies only to special variables.
 int env_set(const wcstring &key, const wchar_t *val, env_mode_flags_t mode);
 
 class env_var_t : public wcstring {
diff --git a/src/event.cpp b/src/event.cpp
index 143992c7e..c215d81fd 100644
--- a/src/event.cpp
+++ b/src/event.cpp
@@ -88,6 +88,10 @@ static int event_match(const event_t &classv, const event_t &instance) {
         case EVENT_GENERIC: {
             return instance.str_param1 == classv.str_param1;
         }
+        default: {
+            DIE("unexpected classv.type");
+            break;
+        }
     }
 
     // This should never be reached.
diff --git a/src/parse_execution.cpp b/src/parse_execution.cpp
index 69bd85632..8887c682a 100644
--- a/src/parse_execution.cpp
+++ b/src/parse_execution.cpp
@@ -534,6 +534,10 @@ parse_execution_result_t parse_execution_context_t::run_switch_statement(
         case EXPAND_OK: {
             break;
         }
+        default: {
+            DIE("unexpected expand_string() return value");
+            break;
+        }
     }
 
     if (result == parse_execution_success && switch_values_expanded.size() != 1) {
@@ -945,6 +949,10 @@ parse_execution_result_t parse_execution_context_t::determine_arguments(
             case EXPAND_OK: {
                 break;
             }
+            default: {
+                DIE("unexpected expand_string() return value");
+                break;
+            }
         }
 
         // Now copy over any expanded arguments. Do it using swap() to avoid extra allocations; this
diff --git a/src/parse_util.cpp b/src/parse_util.cpp
index f0a7f37c5..80c89e160 100644
--- a/src/parse_util.cpp
+++ b/src/parse_util.cpp
@@ -1004,6 +1004,10 @@ parser_test_error_bits_t parse_util_detect_errors_in_argument(const parse_node_t
                 }
                 break;
             }
+            default: {
+                DIE("unexpected parse_util_locate_cmdsubst() return value");
+                break;
+            }
         }
     }
 
diff --git a/src/utf8.cpp b/src/utf8.cpp
index 0e87e50ab..53d994852 100644
--- a/src/utf8.cpp
+++ b/src/utf8.cpp
@@ -20,6 +20,7 @@
 #include <limits>
 #include <string>
 
+#include "common.h"
 #include "utf8.h"
 
 #define _NXT 0x80
@@ -137,9 +138,8 @@ static int __utf8_forbitten(unsigned char octet) {
         case 0xff: {
             return -1;
         }
+        default: { return 0; }
     }
-
-    return 0;
 }
 
 /// This function translates UTF-8 string into UCS-2 or UCS-4 string (all symbols will be in local
@@ -288,18 +288,17 @@ static size_t wchar_to_utf8_internal(const utf8_wchar_t *in, size_t insize, char
             if ((flags & UTF8_IGNORE_ERROR) == 0) return 0;
             continue;
         }
-        if (w_wide <= 0x0000007f)
+        if (w_wide <= 0x0000007f) {
             n = 1;
-        else if (w_wide <= 0x000007ff)
+        } else if (w_wide <= 0x000007ff) {
             n = 2;
-        else if (w_wide <= 0x0000ffff)
+        } else if (w_wide <= 0x0000ffff) {
             n = 3;
-        else if (w_wide <= 0x001fffff)
+        } else if (w_wide <= 0x001fffff) {
             n = 4;
-        else if (w_wide <= 0x03ffffff)
-            n = 5;
-        else
-            n = 6;  /// if (w_wide <= 0x7fffffff)
+        } else {
+            DIE("invalid wide char");
+        }
 
         total += n;
 
@@ -340,10 +339,14 @@ static size_t wchar_to_utf8_internal(const utf8_wchar_t *in, size_t insize, char
                 p[0] = _SEQ4 | ((oc[1] & 0x1f) >> 2);
                 break;
             }
+            default: {
+                DIE("unexpected utff8 len");
+                break;
+            }
         }
 
-        // NOTE: do not check here for forbitten UTF-8 characters. They cannot appear here because
-        // we do proper convertion.
+        // NOTE: do not check here for forbidden UTF-8 characters. They cannot appear here because
+        // we do proper conversion.
         p += n;
     }