diff --git a/drivers/isimodem/call-barring.c b/drivers/isimodem/call-barring.c
index 1508f07e..5eb06cad 100644
--- a/drivers/isimodem/call-barring.c
+++ b/drivers/isimodem/call-barring.c
@@ -49,7 +49,7 @@ struct barr_data {
 	GIsiClient *client;
 };
 
-static int lock_code_to_mmi(char const *lock)
+static int lock_code_to_mmi(const char *lock)
 {
 	if (strcmp(lock, "AO") == 0)
 		return SS_GSM_BARR_ALL_OUT;