diff --git a/CHANGELOG.md b/CHANGELOG.md
index e692a8ef0..e21372ff2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -26,6 +26,7 @@ This section is for changes merged to the `major` branch that are not also merge
 - `bind` has a new `--silent` option to ignore bind requests for named keys not available under the current `$TERMINAL` (#4188, #4431)
 - `read` writes directly to stdout if called without arguments (#4407)
 - Globs are faster (#4579)
+- "Bare variables" in math are no longer accepted. math uses normal variable expansion. (#4393)
 
 ## Other significant changes
 - Command substitution output is now limited to 10 MB by default (#3822).
diff --git a/src/builtin_math.cpp b/src/builtin_math.cpp
index 696749580..8e733b1cb 100644
--- a/src/builtin_math.cpp
+++ b/src/builtin_math.cpp
@@ -115,52 +115,6 @@ static const wchar_t *math_get_arg(int *argidx, wchar_t **argv, wcstring *storag
     return math_get_arg_argv(argidx, argv);
 }
 
-// The MuParser mechanism for dynamic lookup of variables requires that we return a unique address
-// for each variable. The following limit is arbitrary but anyone writing a math expression in fish
-// that references more than one hundred unique variables is abusing fish.
-#define MAX_RESULTS 100
-static double double_results[MAX_RESULTS];
-static int next_result = 0;
-
-/// Return a fish var converted to a double. This allows the user to use a bar var name in the
-/// expression. That is `math a + 1` rather than `math $a + 1`.
-static double *retrieve_var(const wchar_t *var_name, void *user_data) {
-    UNUSED(user_data);
-    static double zero_result = 0.0;
-
-    auto var = env_get(var_name, ENV_DEFAULT);
-    if (!var) {
-        // We could report an error but we normally don't treat missing vars as a fatal error.
-        // throw mu::ParserError(L"Var '%ls' does not exist.");
-        return &zero_result;
-    }
-    if (var->empty()) {
-        return &zero_result;
-    }
-
-    const wchar_t *first_val = var->as_list()[0].c_str();
-    wchar_t *endptr;
-    errno = 0;
-    double result = wcstod(first_val, &endptr);
-    if (*endptr != L'\0' || errno) {
-        wchar_t errmsg[500];
-        swprintf(errmsg, sizeof(errmsg) / sizeof(wchar_t),
-                 _(L"Var '%ls' not a valid floating point number: '%ls'."), var_name, first_val);
-        throw mu::ParserError(errmsg);
-    }
-
-    // We need to return a unique address for the var. If we used a `static double` var and returned
-    // it's address then multiple vars in the expression would all refer to the same value.
-    if (next_result == MAX_RESULTS - 1) {
-        wchar_t errmsg[500];
-        swprintf(errmsg, sizeof(errmsg) / sizeof(wchar_t),
-                 _(L"More than %d var names in math expression."), MAX_RESULTS);
-        throw mu::ParserError(errmsg);
-    }
-    double_results[next_result++] = result;
-    return double_results + next_result - 1;
-}
-
 /// Implement integer modulo math operator.
 static double moduloOperator(double v, double w) { return (int)v % std::max(1, (int)w); };
 
@@ -168,12 +122,9 @@ static double moduloOperator(double v, double w) { return (int)v % std::max(1, (
 static int evaluate_expression(wchar_t *cmd, parser_t &parser, io_streams_t &streams,
                                math_cmd_opts_t &opts, wcstring &expression) {
     UNUSED(parser);
-    next_result = 0;
 
     try {
         mu::Parser p;
-        // Setup callback so variables can be retrieved dynamically.
-        p.SetVarFactory(retrieve_var, nullptr);
         // MuParser doesn't implement the modulo operator so we add it ourselves since there are
         // likely users of our old math wrapper around bc that expect it to be available.
         p.DefineOprtChars(L"%");
diff --git a/tests/math.err b/tests/math.err
index 240044f45..5a7ab5130 100644
--- a/tests/math.err
+++ b/tests/math.err
@@ -3,4 +3,4 @@
 # Validate basic expressions
 
 ####################
-# Validate how bare variables in an epxression are handled
+# Validate how variables in an expression are handled
diff --git a/tests/math.in b/tests/math.in
index 8fee37df4..1e13114d7 100644
--- a/tests/math.in
+++ b/tests/math.in
@@ -14,11 +14,11 @@ math 5 \* -2
 math -- -4 / 2
 math -- '-4 * 2'
 
-logmsg Validate how bare variables in an epxression are handled
-math x + 1
+logmsg Validate how variables in an expression are handled
+math $x + 1
 set x 1
-math x + 1
+math $x + 1
 set x 3
 set y 1.5
-math '-x * y'
-math -s1 '-x * y'
+math "-$x * $y"
+math -s1 "-$x * $y"
diff --git a/tests/math.out b/tests/math.out
index f0a91e8ce..df8607f71 100644
--- a/tests/math.out
+++ b/tests/math.out
@@ -17,7 +17,7 @@
 -8
 
 ####################
-# Validate how bare variables in an epxression are handled
+# Validate how variables in an expression are handled
 1
 2
 -4