diff --git a/datapath-windows/ovsext/Actions.c b/datapath-windows/ovsext/Actions.c
index 0af4a660d4e..9bbc7879e88 100644
--- a/datapath-windows/ovsext/Actions.c
+++ b/datapath-windows/ovsext/Actions.c
@@ -1237,6 +1237,7 @@ OvsActionMplsPush(OvsForwardingContext *ovsFwdCtx,
     ASSERT(mdlLen >= MPLS_HLEN);
 
     ethHdr = (EthHdr *)(bufferStart + curMdlOffset);
+    ASSERT(ethHdr);
     RtlMoveMemory(ethHdr, (UINT8*)ethHdr + MPLS_HLEN, sizeof(*ethHdr));
     ethHdr->Type = mpls->mpls_ethertype;