diff --git a/mozilla/js/src/jsinterp.c b/mozilla/js/src/jsinterp.c
index 4ff5f4f266a..f65f1ec8047 100644
--- a/mozilla/js/src/jsinterp.c
+++ b/mozilla/js/src/jsinterp.c
@@ -5320,7 +5320,7 @@ interrupt:
 
             for (obj = fp->blockChain; obj; obj = OBJ_GET_PARENT(cx, obj)) {
                 JS_ASSERT(OBJ_GET_CLASS(cx, obj) == &js_BlockClass);
-                if (OBJ_BLOCK_DEPTH(cx, obj) + OBJ_BLOCK_COUNT(cx, obj) <= i) {
+                if (OBJ_BLOCK_DEPTH(cx, obj) + (jsint)OBJ_BLOCK_COUNT(cx, obj) <= i) {
                     JS_ASSERT(OBJ_BLOCK_DEPTH(cx, obj) < i || OBJ_BLOCK_COUNT(cx, obj) == 0);
                     break;
                 }