diff --git a/Externals/expr/include/expr.h b/Externals/expr/include/expr.h
index ac15ddef73..c62f68f28d 100644
--- a/Externals/expr/include/expr.h
+++ b/Externals/expr/include/expr.h
@@ -826,14 +826,14 @@ static struct expr *expr_create(const char *s, size_t len,
       vec_push(&es, expr_const(num));
       paren_next = EXPR_PAREN_FORBIDDEN;
     } else if (n > 1 && *tok == '"') {
-      char *s = (char *)calloc(1, n - 1);
-      if (s == NULL) {
+      char *str = (char *)calloc(1, n - 1);
+      if (str == NULL) {
         goto cleanup; /* allocation failed */
       }
-      strncpy(s, tok + 1, n - 2);
+      strncpy(str, tok + 1, n - 2);
       struct expr e = expr_init();
       e.type = OP_STRING;
-      e.param.str.s = s;
+      e.param.str.s = str;
       vec_push(&es, e);
       paren_next = EXPR_PAREN_FORBIDDEN;
     } else if (expr_op(tok, n, -1) != OP_UNKNOWN) {