diff --git a/ChangeLog b/ChangeLog
index 5eac303039..e6c5b83a8d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,4 +1,7 @@
-Tue Oct 12 23:03:20 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+Tue Oct 12 23:09:24 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* gc.c (obj_free, rb_objspace_call_finalizer): fix truncating
+	  cast.
 
 	* gc.c (mark_current_machine_context): suppress warnings.
 
diff --git a/gc.c b/gc.c
index f4ee76d365..b7343fb420 100644
--- a/gc.c
+++ b/gc.c
@@ -2190,7 +2190,7 @@ obj_free(rb_objspace_t *objspace, VALUE obj)
 	    if (RTYPEDDATA_P(obj)) {
 		RDATA(obj)->dfree = RANY(obj)->as.typeddata.type->function.dfree;
 	    }
-	    if ((long)RANY(obj)->as.data.dfree == -1) {
+	    if (RANY(obj)->as.data.dfree == (RUBY_DATA_FUNC)-1) {
 		xfree(DATA_PTR(obj));
 	    }
 	    else if (RANY(obj)->as.data.dfree) {
@@ -2908,7 +2908,7 @@ rb_objspace_call_finalizer(rb_objspace_t *objspace)
 		if (RTYPEDDATA_P(p)) {
 		    RDATA(p)->dfree = RANY(p)->as.typeddata.type->function.dfree;
 		}
-		if ((long)RANY(p)->as.data.dfree == -1) {
+		if (RANY(p)->as.data.dfree == (RUBY_DATA_FUNC)-1) {
 		    xfree(DATA_PTR(p));
 		}
 		else if (RANY(p)->as.data.dfree) {