--- a/src/compiler/fndb.lisp
+++ b/src/compiler/fndb.lisp
@@ -76,6 +76,11 @@
 
 (defknown (eq eql) (t t) boolean (movable foldable flushable))
 (defknown (equal equalp) (t t) boolean (foldable flushable recursive))
+
+#!+(or x86 x86-64)
+(defknown fixnum-mod-p (t fixnum) boolean
+    (movable foldable flushable always-translatable))
+
 
 ;;;; classes