diff --git a/tests/hwsim/test_ap_acs.py b/tests/hwsim/test_ap_acs.py
index 07b567dcc..a7dfd0626 100644
--- a/tests/hwsim/test_ap_acs.py
+++ b/tests/hwsim/test_ap_acs.py
@@ -10,6 +10,7 @@ import subprocess
 import time
 
 import hostapd
+from test_ap_ht import clear_scan_cache
 
 def force_prev_ap_on_24g(ap):
     # For now, make sure the last operating channel was on 2.4 GHz band to get
@@ -92,6 +93,7 @@ def test_ap_multi_bss_acs(dev, apdev):
 
 def test_ap_acs_40mhz(dev, apdev):
     """Automatic channel selection for 40 MHz channel"""
+    clear_scan_cache(apdev[0]['ifname'])
     force_prev_ap_on_24g(apdev[0])
     params = hostapd.wpa2_params(ssid="test-acs", passphrase="12345678")
     params['channel'] = '0'