diff --git a/src/autoload.cpp b/src/autoload.cpp
index bf6828232..6a750cfd3 100644
--- a/src/autoload.cpp
+++ b/src/autoload.cpp
@@ -190,8 +190,7 @@ maybe_t<wcstring> autoload_t::resolve_command(const wcstring &cmd, const environ
     return std::move(mfile->path);
 }
 
-void autoload_t::perform_autoload(const wcstring &path) {
+void autoload_t::perform_autoload(const wcstring &path, parser_t &parser) {
     wcstring script_source = L"source " + escape_string(path, ESCAPE_ALL);
-    exec_subshell(script_source, parser_t::principal_parser(),
-                  false /* do not apply exit status */);
+    exec_subshell(script_source, parser, false /* do not apply exit status */);
 }
diff --git a/src/autoload.h b/src/autoload.h
index 2daed1a45..d59486364 100644
--- a/src/autoload.h
+++ b/src/autoload.h
@@ -15,6 +15,7 @@
 
 class autoload_file_cache_t;
 class environment_t;
+class parser_t;
 
 /// autoload_t is a class that knows how to autoload .fish files from a list of directories. This
 /// is used by autoloading functions and completions. It maintains a file cache, which is
@@ -58,7 +59,7 @@ class autoload_t {
     /// Helper to actually perform an autoload.
     /// This is a static function because it executes fish script, and so must be called without
     /// holding any particular locks.
-    static void perform_autoload(const wcstring &path);
+    static void perform_autoload(const wcstring &path, parser_t &parser);
 
     /// Mark that a command previously returned from path_to_autoload is finished autoloading.
     void mark_autoload_finished(const wcstring &cmd) {
diff --git a/src/builtin_fg.cpp b/src/builtin_fg.cpp
index 7ce712bd7..7a27f254c 100644
--- a/src/builtin_fg.cpp
+++ b/src/builtin_fg.cpp
@@ -101,7 +101,7 @@ int builtin_fg(parser_t &parser, io_streams_t &streams, wchar_t **argv) {
     const wcstring ft = tok_first(job->command());
     //For compatibility with fish 2.0's $_, now replaced with `status current-command`
     if (!ft.empty()) parser.vars().set_one(L"_", ENV_EXPORT, ft);
-    reader_write_title(job->command());
+    reader_write_title(job->command(), parser);
 
     job->promote();
     job->set_flag(job_flag_t::FOREGROUND, true);
diff --git a/src/builtin_functions.cpp b/src/builtin_functions.cpp
index 91b334e6e..16a22128d 100644
--- a/src/builtin_functions.cpp
+++ b/src/builtin_functions.cpp
@@ -225,14 +225,14 @@ static wcstring functions_def(const wcstring &name) {
 }
 
 static int report_function_metadata(const wchar_t *funcname, bool verbose, io_streams_t &streams,
-                                    bool metadata_as_comments) {
+                                    parser_t &parser, bool metadata_as_comments) {
     const wchar_t *path = L"n/a";
     const wchar_t *autoloaded = L"n/a";
     const wchar_t *shadows_scope = L"n/a";
     wcstring description = L"n/a";
     int line_number = 0;
 
-    if (function_exists(funcname)) {
+    if (function_exists(funcname, parser)) {
         auto props = function_get_properties(funcname);
         path = function_get_definition_file(funcname);
         if (path) {
@@ -301,13 +301,13 @@ int builtin_functions(parser_t &parser, io_streams_t &streams, wchar_t **argv) {
         }
 
         func = argv[optind];
-        if (!function_exists(func)) {
+        if (!function_exists(func, parser)) {
             streams.err.append_format(_(L"%ls: Function '%ls' does not exist\n"), cmd, func);
             builtin_print_error_trailer(parser, streams.err, cmd);
             return STATUS_CMD_ERROR;
         }
 
-        function_set_desc(func, opts.description);
+        function_set_desc(func, opts.description, parser);
         return STATUS_CMD_OK;
     }
 
@@ -319,7 +319,7 @@ int builtin_functions(parser_t &parser, io_streams_t &streams, wchar_t **argv) {
         }
 
         const wchar_t *funcname = argv[optind];
-        return report_function_metadata(funcname, opts.verbose, streams, false);
+        return report_function_metadata(funcname, opts.verbose, streams, parser, false);
     }
 
     if (opts.handlers) {
@@ -376,7 +376,7 @@ int builtin_functions(parser_t &parser, io_streams_t &streams, wchar_t **argv) {
         current_func = argv[optind];
         new_func = argv[optind + 1];
 
-        if (!function_exists(current_func)) {
+        if (!function_exists(current_func, parser)) {
             streams.err.append_format(_(L"%ls: Function '%ls' does not exist\n"), cmd,
                                       current_func.c_str());
             builtin_print_error_trailer(parser, streams.err, cmd);
@@ -391,7 +391,7 @@ int builtin_functions(parser_t &parser, io_streams_t &streams, wchar_t **argv) {
         }
 
         // Keep things simple: don't allow existing names to be copy targets.
-        if (function_exists(new_func)) {
+        if (function_exists(new_func, parser)) {
             streams.err.append_format(
                 _(L"%ls: Function '%ls' already exists. Cannot create copy '%ls'\n"), cmd,
                 new_func.c_str(), current_func.c_str());
@@ -405,13 +405,13 @@ int builtin_functions(parser_t &parser, io_streams_t &streams, wchar_t **argv) {
 
     int res = STATUS_CMD_OK;
     for (int i = optind; i < argc; i++) {
-        if (!function_exists(argv[i])) {
+        if (!function_exists(argv[i], parser)) {
             res++;
         } else {
             if (!opts.query) {
                 if (i != optind) streams.out.append(L"\n");
                 const wchar_t *funcname = argv[optind];
-                report_function_metadata(funcname, opts.verbose, streams, true);
+                report_function_metadata(funcname, opts.verbose, streams, parser, true);
                 streams.out.append(functions_def(funcname));
             }
         }
diff --git a/src/complete.cpp b/src/complete.cpp
index d7bb22017..95dffdc9d 100644
--- a/src/complete.cpp
+++ b/src/complete.cpp
@@ -859,7 +859,8 @@ static bool short_ok(const wcstring &arg, const complete_entry_opt_t *entry,
 static void complete_load(const wcstring &name, bool reload) {
     // We have to load this as a function, since it may define a --wraps or signature.
     // See issue #2466.
-    function_load(name);
+    auto &parser = parser_t::principal_parser();
+    function_load(name, parser);
 
     // It's important to NOT hold the lock around completion loading.
     // We need to take the lock to decide what to load, drop it to perform the load, then reacquire
@@ -867,7 +868,7 @@ static void complete_load(const wcstring &name, bool reload) {
     const environment_t &vars = parser_t::principal_parser().vars();
     maybe_t<wcstring> path_to_load = completion_autoloader.acquire()->resolve_command(name, vars);
     if (path_to_load) {
-        autoload_t::perform_autoload(*path_to_load);
+        autoload_t::perform_autoload(*path_to_load, parser);
         completion_autoloader.acquire()->mark_autoload_finished(name);
     }
 }
diff --git a/src/function.cpp b/src/function.cpp
index 75cd7b802..a158027af 100644
--- a/src/function.cpp
+++ b/src/function.cpp
@@ -96,7 +96,7 @@ bool function_set_t::allow_autoload(const wcstring &name) const {
 /// Make sure that if the specified function is a dynamically loaded function, it has been fully
 /// loaded.
 /// Note this executes fish script code.
-static void try_autoload(const wcstring &name) {
+static void try_autoload(const wcstring &name, parser_t &parser) {
     ASSERT_IS_MAIN_THREAD();
     maybe_t<wcstring> path_to_autoload;
     // Note we can't autoload while holding the funcset lock.
@@ -104,15 +104,14 @@ static void try_autoload(const wcstring &name) {
     {
         auto funcset = function_set.acquire();
         if (funcset->allow_autoload(name)) {
-            const environment_t &vars = parser_t::principal_parser().vars();
-            path_to_autoload = funcset->autoloader.resolve_command(name, vars);
+            path_to_autoload = funcset->autoloader.resolve_command(name, parser.vars());
         }
     }
 
     // Release the lock and perform any autoload, then reacquire the lock and clean up.
     if (path_to_autoload) {
         // Crucially, the lock is acquired *after* do_autoload_file_at_path().
-        autoload_t::perform_autoload(*path_to_autoload);
+        autoload_t::perform_autoload(*path_to_autoload, parser);
         function_set.acquire()->autoloader.mark_autoload_finished(name);
     }
 }
@@ -212,18 +211,18 @@ std::shared_ptr<const function_properties_t> function_get_properties(const wcstr
     return nullptr;
 }
 
-int function_exists(const wcstring &cmd) {
+int function_exists(const wcstring &cmd, parser_t &parser) {
     ASSERT_IS_MAIN_THREAD();
     if (parser_keywords_is_reserved(cmd)) return 0;
-    try_autoload(cmd);
+    try_autoload(cmd, parser);
     auto funcset = function_set.acquire();
     return funcset->funcs.find(cmd) != funcset->funcs.end();
 }
 
-void function_load(const wcstring &cmd) {
+void function_load(const wcstring &cmd, parser_t &parser) {
     ASSERT_IS_MAIN_THREAD();
     if (!parser_keywords_is_reserved(cmd)) {
-        try_autoload(cmd);
+        try_autoload(cmd, parser);
     }
 }
 
@@ -279,9 +278,9 @@ bool function_get_desc(const wcstring &name, wcstring &out_desc) {
     return false;
 }
 
-void function_set_desc(const wcstring &name, const wcstring &desc) {
+void function_set_desc(const wcstring &name, const wcstring &desc, parser_t &parser) {
     ASSERT_IS_MAIN_THREAD();
-    try_autoload(name);
+    try_autoload(name, parser);
     auto funcset = function_set.acquire();
     auto iter = funcset->funcs.find(name);
     if (iter != funcset->funcs.end()) {
diff --git a/src/function.h b/src/function.h
index 89179d46f..ad9aee778 100644
--- a/src/function.h
+++ b/src/function.h
@@ -67,14 +67,14 @@ bool function_get_definition(const wcstring &name, wcstring &out_definition);
 bool function_get_desc(const wcstring &name, wcstring &out_desc);
 
 /// Sets the description of the function with the name \c name.
-void function_set_desc(const wcstring &name, const wcstring &desc);
+void function_set_desc(const wcstring &name, const wcstring &desc, parser_t &parser);
 
 /// Returns true if the function with the name name exists.
 /// This may autoload.
-int function_exists(const wcstring &name);
+int function_exists(const wcstring &name, parser_t &parser);
 
 /// Attempts to load a function if not yet loaded. This is used by the completion machinery.
-void function_load(const wcstring &name);
+void function_load(const wcstring &name, parser_t &parser);
 
 /// Returns true if the function with the name name exists, without triggering autoload.
 int function_exists_no_autoload(const wcstring &name, const environment_t &vars);
diff --git a/src/parse_execution.cpp b/src/parse_execution.cpp
index 5ec8152e1..5755a63cb 100644
--- a/src/parse_execution.cpp
+++ b/src/parse_execution.cpp
@@ -164,7 +164,7 @@ process_type_t parse_execution_context_t::process_type_for_command(
             process_type = process_type_t::builtin;
             break;
         case parse_statement_decoration_none:
-            if (function_exists(cmd)) {
+            if (function_exists(cmd, *parser)) {
                 process_type = process_type_t::function;
             } else if (builtin_exists(cmd)) {
                 process_type = process_type_t::builtin;
@@ -858,7 +858,8 @@ parse_execution_result_t parse_execution_context_t::populate_plain_process(
         path_to_external_command.clear();
 
         // If we have defined a wrapper around cd, use it, otherwise use the cd builtin.
-        process_type = function_exists(L"cd") ? process_type_t::function : process_type_t::builtin;
+        process_type =
+            function_exists(L"cd", *parser) ? process_type_t::function : process_type_t::builtin;
     } else {
         // Not implicit cd.
         const globspec_t glob_behavior = (cmd == L"set" || cmd == L"count") ? nullglob : failglob;
diff --git a/src/reader.cpp b/src/reader.cpp
index 473cbac54..3426171d6 100644
--- a/src/reader.cpp
+++ b/src/reader.cpp
@@ -874,11 +874,11 @@ bool reader_thread_job_is_stale() {
     return read_generation_count() != s_thread_generation;
 }
 
-void reader_write_title(const wcstring &cmd, bool reset_cursor_position) {
+void reader_write_title(const wcstring &cmd, parser_t &parser, bool reset_cursor_position) {
     if (!term_supports_setting_title()) return;
 
     wcstring fish_title_command = DEFAULT_TITLE;
-    if (function_exists(L"fish_title")) {
+    if (function_exists(L"fish_title", parser)) {
         fish_title_command = L"fish_title";
         if (!cmd.empty()) {
             fish_title_command.append(L" ");
@@ -889,8 +889,7 @@ void reader_write_title(const wcstring &cmd, bool reset_cursor_position) {
 
     wcstring_list_t lst;
     proc_push_interactive(0);
-    if (exec_subshell(fish_title_command, parser_t::principal_parser(), lst,
-                      false /* ignore exit status */) != -1 &&
+    if (exec_subshell(fish_title_command, parser, lst, false /* ignore exit status */) != -1 &&
         !lst.empty()) {
         std::fputws(L"\x1B]0;", stdout);
         for (size_t i = 0; i < lst.size(); i++) {
@@ -909,7 +908,7 @@ void reader_write_title(const wcstring &cmd, bool reset_cursor_position) {
 
 void reader_data_t::exec_mode_prompt() {
     mode_prompt_buff.clear();
-    if (function_exists(MODE_PROMPT_FUNCTION_NAME)) {
+    if (function_exists(MODE_PROMPT_FUNCTION_NAME, parser())) {
         wcstring_list_t mode_indicator_list;
         exec_subshell(MODE_PROMPT_FUNCTION_NAME, parser(), mode_indicator_list,
                       false);
@@ -966,7 +965,7 @@ void reader_data_t::exec_prompt() {
     // Write the screen title. Do not reset the cursor position: exec_prompt is called when there
     // may still be output on the line from the previous command (#2499) and we need our PROMPT_SP
     // hack to work.
-    reader_write_title(L"", false);
+    reader_write_title(L"", parser(), false);
 }
 
 void reader_init() {
@@ -1957,7 +1956,7 @@ void reader_run_command(parser_t &parser, const wcstring &cmd) {
     if (!ft.empty()) parser.vars().set_one(L"_", ENV_GLOBAL, ft);
 
     outputter_t &outp = outputter_t::stdoutput();
-    reader_write_title(cmd);
+    reader_write_title(cmd, parser);
     term_donate(outp);
 
     gettimeofday(&time_before, NULL);
@@ -2278,15 +2277,15 @@ static int read_i() {
         event_fire_generic(L"fish_prompt");
         run_count++;
 
-        if (is_breakpoint && function_exists(DEBUG_PROMPT_FUNCTION_NAME)) {
+        if (is_breakpoint && function_exists(DEBUG_PROMPT_FUNCTION_NAME, parser)) {
             reader_set_left_prompt(DEBUG_PROMPT_FUNCTION_NAME);
-        } else if (function_exists(LEFT_PROMPT_FUNCTION_NAME)) {
+        } else if (function_exists(LEFT_PROMPT_FUNCTION_NAME, parser)) {
             reader_set_left_prompt(LEFT_PROMPT_FUNCTION_NAME);
         } else {
             reader_set_left_prompt(DEFAULT_PROMPT);
         }
 
-        if (function_exists(RIGHT_PROMPT_FUNCTION_NAME)) {
+        if (function_exists(RIGHT_PROMPT_FUNCTION_NAME, parser)) {
             reader_set_right_prompt(RIGHT_PROMPT_FUNCTION_NAME);
         } else {
             reader_set_right_prompt(L"");
@@ -2500,7 +2499,7 @@ void reader_data_t::handle_readline_command(readline_cmd_t c, readline_loop_stat
             // Repaint the mode-prompt only if it exists.
             // This is an optimization basically exclusively for vi-mode, since the prompt
             // may sometimes take a while but when switching the mode all we care about is the mode-prompt.
-            if (function_exists(MODE_PROMPT_FUNCTION_NAME)) {
+            if (function_exists(MODE_PROMPT_FUNCTION_NAME, parser())) {
                 exec_mode_prompt();
                 s_reset(&screen, screen_reset_current_line_and_prompt);
                 screen_reset_needed = false;
diff --git a/src/reader.h b/src/reader.h
index a6c1bbffb..4be1328a0 100644
--- a/src/reader.h
+++ b/src/reader.h
@@ -82,8 +82,9 @@ void reader_pop_current_filename();
 /// executing and just after it finishes.
 ///
 /// \param cmd Command line string passed to \c fish_title if is defined.
+/// \param parser The parser to use for autoloading fish_title.
 /// \param reset_cursor_position If set, issue a \r so the line driver knows where we are
-void reader_write_title(const wcstring &cmd, bool reset_cursor_position = true);
+void reader_write_title(const wcstring &cmd, parser_t &parser, bool reset_cursor_position = true);
 
 /// Call this function to tell the reader that a repaint is needed, and should be performed when
 /// possible.