diff --git a/src/builtin_math.cpp b/src/builtin_math.cpp
index 5ccae2ca1..07c9b3e44 100644
--- a/src/builtin_math.cpp
+++ b/src/builtin_math.cpp
@@ -223,11 +223,6 @@ static int evaluate_expression(const wchar_t *cmd, const parser_t &parser, io_st
 
     int retval = STATUS_CMD_OK;
     te_error_t error;
-    // Switch locale while computing stuff.
-    // This means that the "." is always the radix character,
-    // so numbers work the same across locales.
-    char *saved_locale = strdup(setlocale(LC_NUMERIC, nullptr));
-    setlocale(LC_NUMERIC, "C");
     double v = te_interp(expression.c_str(), &error);
 
     if (error.position == 0) {
@@ -257,8 +252,6 @@ static int evaluate_expression(const wchar_t *cmd, const parser_t &parser, io_st
         streams.err.append_format(L"%*ls%ls\n", error.position - 1, L" ", L"^");
         retval = STATUS_CMD_ERROR;
     }
-    setlocale(LC_NUMERIC, saved_locale);
-    free(saved_locale);
     return retval;
 }
 
diff --git a/src/tinyexpr.cpp b/src/tinyexpr.cpp
index ffe9f0efe..8413d8530 100644
--- a/src/tinyexpr.cpp
+++ b/src/tinyexpr.cpp
@@ -24,6 +24,7 @@
 
 // This version has been altered and ported to C++ for inclusion in fish.
 #include "tinyexpr.h"
+#include "wutil.h"
 
 #include <ctype.h>
 #include <limits.h>
@@ -250,7 +251,7 @@ static void next_token(state *s) {
 
         /* Try reading a number. */
         if ((s->next[0] >= '0' && s->next[0] <= '9') || s->next[0] == '.') {
-            s->value = wcstod(s->next, const_cast<wchar_t **>(&s->next));
+            s->value = wcstod_l(s->next, const_cast<wchar_t **>(&s->next), fish_c_locale());
             s->type = TOK_NUMBER;
         } else {
             /* Look for a function call. */