diff --git a/src/builtin_printf.cpp b/src/builtin_printf.cpp
index d5fa1d638..cfefba89a 100644
--- a/src/builtin_printf.cpp
+++ b/src/builtin_printf.cpp
@@ -172,35 +172,9 @@ static int octal_to_bin(wchar_t c)
     }
 }
 
-/* This message appears in N_() here rather than just in _() below because
-   the sole use would have been in a #define.  */
-static wchar_t const *const cfcc_msg =
-    N_(L"warning: %ls: character(s) following character constant have been ignored");
-
-double C_STRTOD(wchar_t const *nptr, wchar_t **endptr)
-{
-    double r;
-
-    const wcstring saved_locale = wsetlocale(LC_NUMERIC, NULL);
-
-    if (!saved_locale.empty())
-    {
-        wsetlocale(LC_NUMERIC, L"C");
-    }
-
-    r = wcstod(nptr, endptr);
-
-    if (!saved_locale.empty())
-    {
-        wsetlocale(LC_NUMERIC, saved_locale.c_str());
-    }
-
-    return r;
-}
-
 void builtin_printf_state_t::fatal_error(const wchar_t *fmt, ...)
 {
-    // Don't error twice
+    // Don't error twice.
     if (early_exit)
         return;
 
@@ -279,10 +253,14 @@ uintmax_t raw_string_to_scalar_type(const wchar_t *s, wchar_t ** end)
     return wcstoull(s, end, 0);
 }
 
-template<>
-long double raw_string_to_scalar_type(const wchar_t *s, wchar_t ** end)
-{
-    return C_STRTOD(s, end);
+template <>
+long double raw_string_to_scalar_type(const wchar_t *s, wchar_t **end) {
+    // Forcing the locale to C is questionable but it's what the old C_STRTOD() that I inlined here
+    // as part of changing how locale management is done by fish.
+    char * old_locale = setlocale(LC_NUMERIC, "C");
+    double val = wcstod(s, end);
+    setlocale(LC_NUMERIC, old_locale);
+    return val;
 }
 
 template<typename T>
diff --git a/src/common.cpp b/src/common.cpp
index b341f226f..49405f1df 100644
--- a/src/common.cpp
+++ b/src/common.cpp
@@ -6,7 +6,24 @@ parts of fish.
 
 #include "config.h"
 
-
+#include <assert.h>
+#include <cxxabi.h>
+#include <dlfcn.h>
+#include <errno.h>
+#include <limits.h>
+#include <math.h>
+#include <signal.h>
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <termios.h>
 #include <unistd.h>
 
 #ifdef HAVE_SIGINFO_H
@@ -533,26 +550,12 @@ wchar_t *quote_end(const wchar_t *pos)
 
 }
 
-
-wcstring wsetlocale(int category, const wchar_t *locale)
-{
-
-    char *lang = locale ? wcs2str(locale) : NULL;
-    char *res = setlocale(category, lang);
-    free(lang);
-
-    /*
-      Use ellipsis if on known unicode system, otherwise use $
-    */
+void fish_setlocale() {
+    // Use ellipsis if on known unicode system, otherwise use $.
     ellipsis_char = (wcwidth(L'\x2026') > 0) ? L'\x2026' : L'$';
 
     // U+23CE is the "return" character
     omitted_newline_char = (wcwidth(L'\x23CE') > 0) ? L'\x23CE' : L'~';
-
-    if (!res)
-        return wcstring();
-    else
-        return format_string(L"%s", res);
 }
 
 bool contains_internal(const wchar_t *a, int vararg_handle, ...)
diff --git a/src/common.h b/src/common.h
index 18b71cb64..7690f40d6 100644
--- a/src/common.h
+++ b/src/common.h
@@ -763,13 +763,9 @@ wchar_t *quote_end(const wchar_t *in);
 */
 void error_reset();
 
-/**
-   This function behaves exactly like a wide character equivalent of
-   the C function setlocale, except that it will also try to detect if
-   the user is using a Unicode character set, and if so, use the
-   unicode ellipsis character as ellipsis, instead of '$'.
-*/
-wcstring wsetlocale(int category, const wchar_t *locale);
+/// This function should be called after calling `setlocale()` to perform fish specific locale
+/// initialization.
+void fish_setlocale();
 
 /**
    Checks if \c needle is included in the list of strings specified. A warning is printed if needle is zero.
diff --git a/src/env.cpp b/src/env.cpp
index 56c9deb07..b6a402acd 100644
--- a/src/env.cpp
+++ b/src/env.cpp
@@ -3,39 +3,39 @@
 */
 #include "config.h" // IWYU pragma: keep
 
-#include <stdlib.h>
-#include <wchar.h>
-#include <locale.h>
-#include <unistd.h>
+#include <algorithm>
 #include <assert.h>
-#include <sys/stat.h>
+#include <errno.h>
+#include <locale.h>
+#include <map>
 #include <pthread.h>
 #include <pwd.h>
 #include <set>
-#include <map>
-#include <algorithm>
-#include <errno.h>
 #include <stddef.h>
-#include <wctype.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
 #include <utility>
 #include <vector>
+#include <wchar.h>
+#include <wctype.h>
 
-#include "fallback.h"
-
-#include "wutil.h"
-#include "proc.h"
 #include "common.h"
 #include "env.h"
-#include "sanity.h"
-#include "expand.h"
-#include "history.h"
-#include "reader.h"
 #include "env_universal_common.h"
-#include "input.h"
 #include "event.h"
-#include "path.h"
-
+#include "expand.h"
+#include "fallback.h"
 #include "fish_version.h"
+#include "history.h"
+#include "input.h"
+#include "path.h"
+#include "proc.h"
+#include "reader.h"
+#include "sanity.h"
+#include "wutil.h"
 
 /** Value denoting a null string */
 #define ENV_NULL L"\x1d"
@@ -168,22 +168,15 @@ static void mark_changed_exported()
     has_changed_exported = true;
 }
 
-/**
-   List of all locale variable names
-*/
-static const wchar_t * const locale_variable[] =
-{
-    L"LANG",
-    L"LC_ALL",
-    L"LC_COLLATE",
-    L"LC_CTYPE",
-    L"LC_MESSAGES",
-    L"LC_MONETARY",
-    L"LC_NUMERIC",
-    L"LC_TIME",
-    NULL
-};
+/// List of all locale environment variable names.
+static const wchar_t *const locale_variable[] = {
+    L"LANG",     L"LANGUAGE",          L"LC_ALL",         L"LC_ADDRESS",   L"LC_COLLATE",
+    L"LC_CTYPE", L"LC_IDENTIFICATION", L"LC_MEASUREMENT", L"LC_MESSAGES",  L"LC_MONETARY",
+    L"LC_NAME",  L"LC_NUMERIC",        L"LC_PAPER",       L"LC_TELEPHONE", L"LC_TIME",
+    NULL};
 
+/// List of all curses environment variable names.
+static const wchar_t *const curses_variable[] = {L"TERM", L"TERMINFO", L"TERMINFO_DIRS", NULL};
 
 const var_entry_t *env_node_t::find_entry(const wcstring &key)
 {
@@ -231,65 +224,34 @@ static bool var_is_locale(const wcstring &key)
     return false;
 }
 
-/**
-  Properly sets all locale information
-*/
-static void handle_locale()
-{
-    const env_var_t lc_all = env_get_string(L"LC_ALL");
-    const wcstring old_locale = wsetlocale(LC_MESSAGES, NULL);
+/// Properly sets all locale information.
+static void handle_locale(const wchar_t *env_var_name) {
+    debug(2, L"handle_locale() called in response to '%ls' changing", env_var_name);
+    const char *old_msg_locale = setlocale(LC_MESSAGES, NULL);
 
-    /*
-      Array of locale constants corresponding to the local variable names defined in locale_variable
-    */
-    static const int cat[] =
-    {
-        0,
-        LC_ALL,
-        LC_COLLATE,
-        LC_CTYPE,
-        LC_MESSAGES,
-        LC_MONETARY,
-        LC_NUMERIC,
-        LC_TIME
-    }
-    ;
-
-    if (!lc_all.missing())
-    {
-        wsetlocale(LC_ALL, lc_all.c_str());
-    }
-    else
-    {
-        const env_var_t lang = env_get_string(L"LANG");
-        if (!lang.missing())
-        {
-            wsetlocale(LC_ALL, lang.c_str());
-        }
-
-        for (int i=2; locale_variable[i]; i++)
-        {
-            const env_var_t val = env_get_string(locale_variable[i]);
-
-            if (!val.missing())
-            {
-                wsetlocale(cat[i], val.c_str());
-            }
+    for (size_t i = 0; locale_variable[i]; i++) {
+        const wchar_t *key = locale_variable[i];
+        const env_var_t var = env_get_string(key);
+        if (!var.empty()) {
+            const std::string &name = wcs2string(key);
+            const std::string &value = wcs2string(var);
+            setenv(name.c_str(), value.c_str(), 1);
+            debug(3, L"locale var %s='%s'", name.c_str(), value.c_str());
         }
     }
 
-    const wcstring new_locale = wsetlocale(LC_MESSAGES, NULL);
-    if (old_locale != new_locale)
-    {
-
-        /*
-           Try to make change known to gettext. Both changing
-           _nl_msg_cat_cntr and calling dcgettext might potentially
-           tell some gettext implementation that the translation
-           strings should be reloaded. We do both and hope for the
-           best.
-        */
+    char *locale = setlocale(LC_ALL, "");
+    fish_setlocale();
+    debug(2, L"handle_locale() setlocale(): '%s'", locale);
 
+    const char *new_msg_locale = setlocale(LC_MESSAGES, NULL);
+    debug(3, L"old LC_MESSAGES locale: '%s'", old_msg_locale);
+    debug(3, L"new LC_MESSAGES locale: '%s'", new_msg_locale);
+    if (strcmp(old_msg_locale, new_msg_locale)) {
+        // Try to make change known to gettext. Both changing _nl_msg_cat_cntr and calling dcgettext
+        // might potentially tell some gettext implementation that the translation strings should be
+        // reloaded. We do both and hope for the best.
+        debug(2, L"changing message locale from '%s' to '%s'", old_msg_locale, new_msg_locale);
         extern int _nl_msg_cat_cntr;
         _nl_msg_cat_cntr++;
 
@@ -297,16 +259,43 @@ static void handle_locale()
     }
 }
 
-
-/** React to modifying the given variable */
-static void react_to_variable_change(const wcstring &key)
-{
-    if (var_is_locale(key))
-    {
-        handle_locale();
+/// Check if the specified variable is a locale variable.
+static bool var_is_curses(const wcstring &key) {
+    for (size_t i = 0; curses_variable[i]; i++) {
+        if (key == curses_variable[i]) {
+            return true;
+        }
     }
-    else if (key == L"fish_term256" || key == L"fish_term24bit")
-    {
+    return false;
+}
+
+/// Push all curses/terminfo env vars into the global environment where they can be found by those
+/// libraries.
+static void handle_curses(const wchar_t *env_var_name) {
+    debug(2, L"handle_curses() called in response to '%ls' changing", env_var_name);
+    for (size_t i = 0; curses_variable[i]; i++) {
+        const wchar_t *key = curses_variable[i];
+        const env_var_t var = env_get_string(key);
+        if (!var.empty()) {
+            const std::string &name = wcs2string(key);
+            const std::string &value = wcs2string(var);
+            setenv(name.c_str(), value.c_str(), 1);
+            debug(3, L"curses var %s='%s'", name.c_str(), value.c_str());
+        }
+    }
+    // TODO: Modify input_init() to allow calling it when the terminfo env vars are dynamically
+    // changed. At the present time it can be called just once. Also, we should really only do this
+    // if the TERM var is set.
+    // input_init();
+}
+
+/// React to modifying the given variable.
+static void react_to_variable_change(const wcstring &key) {
+    if (var_is_locale(key)) {
+        handle_locale(key.c_str());
+    } else if (var_is_curses(key)) {
+        handle_curses(key.c_str());
+    } else if (key == L"fish_term256" || key == L"fish_term24bit") {
         update_fish_color_support();
         reader_react_to_color_change();
     }
@@ -1119,16 +1108,13 @@ void env_pop()
     if (&top->env != global)
     {
         int i;
-        int locale_changed = 0;
-
+        const wchar_t *locale_changed = NULL;
         env_node_t *killme = top;
 
-        for (i=0; locale_variable[i]; i++)
-        {
-            var_table_t::iterator result =  killme->env.find(locale_variable[i]);
-            if (result != killme->env.end())
-            {
-                locale_changed = 1;
+        for (i = 0; locale_variable[i]; i++) {
+            var_table_t::iterator result = killme->env.find(locale_variable[i]);
+            if (result != killme->env.end()) {
+                locale_changed = locale_variable[i];
                 break;
             }
         }
@@ -1154,8 +1140,7 @@ void env_pop()
 
         delete killme;
 
-        if (locale_changed)
-            handle_locale();
+        if (locale_changed) handle_locale(locale_changed);
 
     }
     else
diff --git a/src/fish.cpp b/src/fish.cpp
index 39c9d5eb2..9b73342e2 100644
--- a/src/fish.cpp
+++ b/src/fish.cpp
@@ -511,11 +511,12 @@ int main(int argc, char **argv)
     assert(R_SENTINAL >= INPUT_COMMON_BASE &&
            R_SENTINAL <= INPUT_COMMON_END);
 
+    program_name = L"fish";
     set_main_thread();
     setup_fork_guards();
 
-    wsetlocale(LC_ALL, L"");
-    program_name=L"fish";
+    setlocale(LC_ALL, "");
+    fish_setlocale();
 
     //struct stat tmp;
     //stat("----------FISH_HIT_MAIN----------", &tmp);
diff --git a/src/fish_indent.cpp b/src/fish_indent.cpp
index 0e31f28e7..a965c4e14 100644
--- a/src/fish_indent.cpp
+++ b/src/fish_indent.cpp
@@ -319,12 +319,16 @@ static std::string no_colorize(const wcstring &text)
 
 int main(int argc, char *argv[])
 {
+    program_name = L"fish_indent";
     set_main_thread();
     setup_fork_guards();
-
-    wsetlocale(LC_ALL, L"");
-    program_name=L"fish_indent";
-
+    // Using the user's default locale could be a problem if it doesn't use UTF-8 encoding. That's
+    // because the fish project assumes Unicode UTF-8 encoding in all of its scripts.
+    //
+    // TODO: Auto-detect the encoding of the script. We should look for a vim style comment
+    // (e.g., "# vim: set fileencoding=<encoding-name>:") or an emacs style comment
+    // (e.g., "# -*- coding: <encoding-name> -*-").
+    setlocale(LC_ALL, "");
     env_init();
     input_init();
 
diff --git a/src/fish_key_reader.cpp b/src/fish_key_reader.cpp
index 5a33feeec..c0e98832c 100644
--- a/src/fish_key_reader.cpp
+++ b/src/fish_key_reader.cpp
@@ -146,8 +146,7 @@ void setup_and_process_keys(bool continuous_mode) {
     is_interactive_session = 1;  // by definition this is interactive
     set_main_thread();
     setup_fork_guards();
-    wsetlocale(LC_ALL, L"POSIX");
-    program_name = L"fish_key_reader";
+    setlocale(LC_ALL, "POSIX");
     env_init();
     reader_init();
     input_init();
@@ -176,6 +175,7 @@ void setup_and_process_keys(bool continuous_mode) {
 }
 
 int main(int argc, char **argv) {
+    program_name = L"fish_key_reader";
     bool continuous_mode = false;
     const char *short_opts = "+c";
     const struct option long_opts[] = {{"continuous", no_argument, NULL, 'd'}, {NULL, 0, NULL, 0}};
diff --git a/tests/test_util.fish b/tests/test_util.fish
index 7e8f1fd68..22c478524 100644
--- a/tests/test_util.fish
+++ b/tests/test_util.fish
@@ -1,4 +1,4 @@
-# vim: set ts=4 sw=4 et:
+# vim: set ts=4 sw=4 tw=100 et:
 # Utilities for the test runners
 
 if test "$argv[1]" = (status -f)
@@ -19,14 +19,12 @@ function die
     exit 1
 end
 
-# Check if we're running in the test environment.
-# If not, set it up and rerun fish with exec.
-# The test is whether the special var __fish_is_running_tests
-# exists and contains the same value as XDG_CONFIG_HOME. It checks
-# the value and not just the presence because we're going to delete
-# the config directory later if we're exiting successfully.
+# Check if we're running in the test environment.  If not, set it up and rerun fish with exec.  The
+# test is whether the special var __fish_is_running_tests exists and contains the same value as
+# XDG_CONFIG_HOME. It checks the value and not just the presence because we're going to delete the
+# config directory later if we're exiting successfully.
 if not set -q __fish_is_running_tests
-    # set up our test environment and re-run the original script
+    # Set up our test environment and re-run the original script.
     set -l script $argv[1]
     switch $script
     case '/*'
@@ -35,8 +33,11 @@ if not set -q __fish_is_running_tests
         # path is relative, make it absolute
         set script $PWD/$script
     end
-    set -l IFS # clear IFS so cmd substitution doesn't split
-    cd (dirname $script); or die
+
+    begin
+        set -l IFS  # clear IFS so cmd substitution doesn't split
+        cd (dirname $script); or die
+    end
 
     set -lx XDG_DATA_HOME ../test/data
     rm -rf $XDG_DATA_HOME/fish
@@ -52,13 +53,21 @@ if not set -q __fish_is_running_tests
     printf 'set fish_function_path \'%s/functions\' \'%s/share/functions\'\n' $escaped_config $escaped_parent > $XDG_CONFIG_HOME/fish/config.fish; or die
     set -xl __fish_is_running_tests $XDG_CONFIG_HOME
 
-    # set locale information to be consistent
-    set -lx LANG C
-    set -lx LC_ALL ''
-    for var in ALL COLLATE MESSAGES MONETARY NUMERIC TIME
-        set -lx LC_$var ''
+    # Set locale information for consistent tests. Fish should work with a lot of locales but the
+    # tests assume an english UTF-8 locale unless they explicitly override this default. We do not
+    # want the users locale to affect the tests since they might, for example, change the wording of
+    # logged messages.
+    #
+    # TODO: set LANG to en_US.UTF-8 so we test the locale message conversions (i.e., gettext).
+    set -e LANGUAGE
+    set -x LANG C
+    # Remove "LC_" env vars from the test environment.
+    for var in (set -xn)
+        string match -q 'LC_*' $var
+        and set -e $var
     end
-    set -lx LC_CTYPE en_US.UTF-8
+    set -x LC_CTYPE en_US.UTF-8
+
     exec ../test/root/bin/fish $script $args_for_test_script
     die 'exec failed'
 else if test "$__fish_is_running_tests" != "$XDG_CONFIG_HOME"