diff --git a/sys/dev/rtwn/if_rtwn_rx.c b/sys/dev/rtwn/if_rtwn_rx.c
--- a/sys/dev/rtwn/if_rtwn_rx.c
+++ b/sys/dev/rtwn/if_rtwn_rx.c
@@ -318,6 +318,10 @@
 	/* Drop PHY descriptor. */
 	m_adj(m, infosz + shift);
 
+	/* If APPFCS, drop FCS */
+	if (sc->rcr & R92C_RCR_APPFCS)
+		m_adj(m, -IEEE80211_CRC_LEN);
+
 	return (ni);
 }
 
@@ -456,6 +460,15 @@
 	    R92C_RCR_HTC_LOC_CTRL | R92C_RCR_APP_PHYSTS |
 	    R92C_RCR_APP_ICV | R92C_RCR_APP_MIC;
 
+	/*
+	 * Add FCS, to work around occasional 4 byte truncation
+	 * with some frames.  This is more problematic on RTL8812/
+	 * RTL8821 because they're also doing L3/L4 checksum offload
+	 * and hardware encryption, so both are tagged as "passed"
+	 * before the frame is truncated.
+	 */
+	sc->rcr |= R92C_RCR_APPFCS;
+
 	/* Update dynamic Rx filter parts. */
 	rtwn_rxfilter_update(sc);
 }
@@ -487,7 +500,7 @@
 	RTWN_ASSERT_LOCKED(sc);
 
 	mask_all = R92C_RCR_ACF | R92C_RCR_ADF | R92C_RCR_AMF | R92C_RCR_AAP;
-	mask_min = R92C_RCR_APM;
+	mask_min = R92C_RCR_APM | R92C_RCR_APPFCS;
 
 	if (sc->bcn_vaps == 0)
 		mask_min |= R92C_RCR_CBSSID_BCN;