diff --git a/cmd/postpolicyform.go b/cmd/postpolicyform.go
index 16addbcc5..d4d1c214a 100644
--- a/cmd/postpolicyform.go
+++ b/cmd/postpolicyform.go
@@ -364,7 +364,7 @@ func checkPostPolicy(formValues http.Header, postPolicyForm PostPolicyForm) erro
 		for key := range checkHeader {
 			logKeys = append(logKeys, key)
 		}
-		return fmt.Errorf("Each form field that you specify in a form (except %s) must appear in the list of conditions.", strings.Join(logKeys, ", "))
+		return fmt.Errorf("Each form field that you specify in a form must appear in the list of policy conditions. %q not specified in the policy.", strings.Join(logKeys, ", "))
 	}
 
 	return nil