diff --git a/src/mzscheme/src/bignum.c b/src/mzscheme/src/bignum.c
index 46d4493beb..eec7d91266 100644
--- a/src/mzscheme/src/bignum.c
+++ b/src/mzscheme/src/bignum.c
@@ -890,14 +890,15 @@ Scheme_Object *scheme_generic_integer_power(const Scheme_Object *a, const Scheme
 
   if (scheme_current_thread->constant_folding) {
     /* if we're trying to fold a constant, limit the work that we're willing to do at compile time */
+    GC_CAN_IGNORE const char *too_big = "arguments too big to fold `expt'";
     if (SCHEME_BIGNUMP(b)
         || (SCHEME_INT_VAL(b) > 10000))
-      scheme_signal_error("too big");
+      scheme_signal_error(too_big);
     else if (SCHEME_BIGNUMP(a)) {
       int len = SCHEME_BIGLEN(a);
       if ((len > 10000)
           || (len * SCHEME_INT_VAL(b)) > 10000)
-        scheme_signal_error("too big");
+        scheme_signal_error(too_big);
     }
   }