diff --git a/racket/src/expander/read/number.rkt b/racket/src/expander/read/number.rkt
index 03a2d009a4..4f859e01da 100644
--- a/racket/src/expander/read/number.rkt
+++ b/racket/src/expander/read/number.rkt
@@ -448,7 +448,7 @@
                                            'read)))
         (cond
           [(or (not n) (string? n))
-           (error 'string->number "host `string->number` failed on ~s" (substring s start end))]
+           (error 'string->number "host `string->number` failed on ~s with radix ~s" (substring s start end) radix)]
           [(eq? exactness 'inexact)
            (cond
              [(extflonum? n)
diff --git a/racket/src/racket/src/startup.inc b/racket/src/racket/src/startup.inc
index 78137001ba..2fdf175e9c 100644
--- a/racket/src/racket/src/startup.inc
+++ b/racket/src/racket/src/startup.inc
@@ -54696,8 +54696,9 @@ static const char *startup_source =
 "(let-values()"
 "(error"
 " 'string->number"
-"                               \"host `string->number` failed on ~s\""
-"(substring s_0 start_0 end_0)))"
+"                               \"host `string->number` failed on ~s with radix ~s\""
+"(substring s_0 start_0 end_0)"
+" radix_0))"
 "(if(eq? exactness_0 'inexact)"
 "(let-values()"
 "(if(extflonum? n_0)"