diff --git a/src/eval.c b/src/eval.c
index 9d4079d..72b1d6c 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -4089,7 +4089,7 @@
 	    else
 	    {
 		name = deref;
-		len = STRLEN(name);
+		len = (long)STRLEN(name);
 	    }
 	    *paren = '(';
 	}