diff --git a/library/test/crashes.factor b/library/test/crashes.factor
index 894cf0affe..f9fda23a92 100644
--- a/library/test/crashes.factor
+++ b/library/test/crashes.factor
@@ -29,3 +29,5 @@ prettyprint sequences strings test vectors words ;
     full-gc
     full-gc
 ] unit-test
+
+[ ] [ f size ] unit-test
diff --git a/native/memory.c b/native/memory.c
index 245b982f6d..9d9d353e20 100644
--- a/native/memory.c
+++ b/native/memory.c
@@ -25,7 +25,10 @@ CELL object_size(CELL pointer)
 		size = sizeof(F_CONS);
 		break;
 	case OBJECT_TYPE:
-		size = untagged_object_size(UNTAG(pointer));
+		if(pointer == F)
+			size = 0;
+		else
+			size = untagged_object_size(UNTAG(pointer));
 		break;
 	default:
 		critical_error("Cannot determine object_size",pointer);
@@ -40,9 +43,6 @@ CELL untagged_object_size(CELL pointer)
 {
 	CELL size;
 
-	if(pointer == F)
-		return 0;
-
 	switch(untag_header(get(pointer)))
 	{
 	case WORD_TYPE: