diff --git a/tools/env/fw_env.c b/tools/env/fw_env.c
index 9b023e8..02f97c0 100644
--- a/tools/env/fw_env.c
+++ b/tools/env/fw_env.c
@@ -379,7 +379,8 @@ int fw_env_write(char *name, char *value)
  */
 int fw_setenv(int argc, char *argv[])
 {
-	int i, len;
+	int i;
+	size_t len;
 	char *name;
 	char *value = NULL;