diff --git a/openbsc/src/libctrl/control_if.c b/openbsc/src/libctrl/control_if.c
index d081342..cc5709d 100644
--- a/openbsc/src/libctrl/control_if.c
+++ b/openbsc/src/libctrl/control_if.c
@@ -518,7 +518,7 @@
 
 	talloc_free(dup);
 
-	cmd->reply = talloc_asprintf(cmd, "%lu", get_rate_ctr_value(ctr, intv));
+	cmd->reply = talloc_asprintf(cmd, "%"PRIu64, get_rate_ctr_value(ctr, intv));
 	if (!cmd->reply)
 		goto oom;