diff --git a/src/iodine.c b/src/iodine.c
index 2caef1f..4de0790 100644
--- a/src/iodine.c
+++ b/src/iodine.c
@@ -98,7 +98,7 @@ build_hostname(char *buf, size_t buflen,
 		const char *topdomain)
 {
 	int encsize;
-	unsigned space;
+	size_t space;
 	char *b;