diff --git a/cmd/zhack/zhack.c b/cmd/zhack/zhack.c
index 70f88fc698..e15af8f4ea 100644
--- a/cmd/zhack/zhack.c
+++ b/cmd/zhack/zhack.c
@@ -268,7 +268,7 @@ zhack_feature_enable_sync(void *arg, dmu_tx_t *tx)
 static void
 zhack_do_feature_enable(int argc, char **argv)
 {
-	char c;
+	int c;
 	char *desc, *target;
 	spa_t *spa;
 	objset_t *mos;
@@ -363,7 +363,7 @@ feature_decr_sync(void *arg, dmu_tx_t *tx)
 static void
 zhack_do_feature_ref(int argc, char **argv)
 {
-	char c;
+	int c;
 	char *target;
 	boolean_t decr = B_FALSE;
 	spa_t *spa;
@@ -483,7 +483,7 @@ main(int argc, char **argv)
 	char *path[MAX_NUM_PATHS];
 	const char *subcommand;
 	int rv = 0;
-	char c;
+	int c;
 
 	g_importargs.path = path;