diff --git a/variable.c b/variable.c
index 35ba4f2..ca33a4c 100644
--- a/variable.c
+++ b/variable.c
@@ -30,7 +30,7 @@
 #include "hash.h"
 
 /* Incremented every time we add or remove a global variable.  */
-static unsigned int variable_changenum;
+static unsigned long variable_changenum;
 
 /* Chain of all pattern-specific variables.  */