diff --git a/encoding.c b/encoding.c
index 66e63b5..3f5d8b4 100644
--- a/encoding.c
+++ b/encoding.c
@@ -1239,7 +1239,7 @@
     const char *alias;
     char upper[500];
     int i;
-    char *up = 0;
+    char *up = NULL;
 
     /*
      * Do the alias resolution