misc: Use NULL instead of integer value for a NULL pointer
diff --git a/openbsc/src/chan_alloc.c b/openbsc/src/chan_alloc.c
index 48c728c..541c6c3 100644
--- a/openbsc/src/chan_alloc.c
+++ b/openbsc/src/chan_alloc.c
@@ -227,7 +227,7 @@
 	lchan->type = GSM_LCHAN_NONE;
 	if (lchan->subscr) {
 		subscr_put(lchan->subscr);
-		lchan->subscr = 0;
+		lchan->subscr = NULL;
 	}
 
 	/* We might kill an active channel... */
@@ -304,5 +304,5 @@
 			return lchan;
 	}
 
-	return 0;
+	return NULL;
 }