diff --git a/nimble/controller/syscfg.yml b/nimble/controller/syscfg.yml
index 03b662d5f..46ece56ea 100644
--- a/nimble/controller/syscfg.yml
+++ b/nimble/controller/syscfg.yml
@@ -317,3 +317,6 @@ syscfg.vals.BLE_LL_CFG_FEAT_LL_EXT_ADV:
 # controller code visible when connected to external host
 syscfg.vals.!BLE_HOST:
     BLE_LL_VND_EVENT_ON_ASSERT: 1
+
+syscfg.restrictions:
+    - OS_CPUTIME_FREQ == 32768