diff --git a/dlls/rpcrt4/rpc_binding.c b/dlls/rpcrt4/rpc_binding.c
index bec104235a4..f8e2451ad18 100644
--- a/dlls/rpcrt4/rpc_binding.c
+++ b/dlls/rpcrt4/rpc_binding.c
@@ -399,7 +399,7 @@ RPC_STATUS RPCRT4_SetBindingObject(RpcBinding* Binding, UUID* ObjectUuid)
 RPC_STATUS RPCRT4_MakeBinding(RpcBinding** Binding, RpcConnection* Connection)
 {
   RpcBinding* NewBinding;
-  TRACE("(*RpcBinding == ^%p, Connection == ^%p)\n", *Binding, Connection);
+  TRACE("(RpcBinding == ^%p, Connection == ^%p)\n", Binding, Connection);
 
   RPCRT4_AllocBinding(&NewBinding, Connection->server);
   NewBinding->Protseq = RPCRT4_strdupA(Connection->Protseq);
@@ -1096,3 +1096,22 @@ RPC_STATUS WINAPI RpcNetworkIsProtseqValidW(LPWSTR protseq) {
   FIXME("Unknown protseq %s - we probably need to implement it one day\n", debugstr_w(protseq));
   return RPC_S_PROTSEQ_NOT_SUPPORTED;
 }
+
+/***********************************************************************
+ *             RpcImpersonateClient (RPCRT4.@)
+ *
+ * Impersonates the client connected via a binding handle so that security
+ * checks are done in the context of the client.
+ *
+ * PARAMS
+ *  BindingHandle [I] Handle to the binding to the client.
+ *
+ * RETURNS
+ *  Success: RPS_S_OK.
+ *  Failure: RPC_STATUS value.
+ */
+RPC_STATUS WINAPI RpcImpersonateClient(RPC_BINDING_HANDLE BindingHandle)
+{
+    FIXME("(%p): stub\n", BindingHandle);
+    return RPC_S_NO_CONTEXT_AVAILABLE;
+}
diff --git a/dlls/rpcrt4/rpc_message.c b/dlls/rpcrt4/rpc_message.c
index cd87c48ef71..080db93a316 100644
--- a/dlls/rpcrt4/rpc_message.c
+++ b/dlls/rpcrt4/rpc_message.c
@@ -317,6 +317,7 @@ RPC_STATUS RPCRT4_Receive(RpcConnection *Connection, RpcPktHdr **Header,
     }
   }
   if (dwRead != sizeof(common_hdr)) {
+    WARN("Short read of header, %ld/%d bytes\n", dwRead, sizeof(common_hdr));
     status = RPC_S_PROTOCOL_ERROR;
     goto fail;
   }
@@ -331,6 +332,7 @@ RPC_STATUS RPCRT4_Receive(RpcConnection *Connection, RpcPktHdr **Header,
 
   hdr_length = RPCRT4_GetHeaderSize((RpcPktHdr*)&common_hdr);
   if (hdr_length == 0) {
+    WARN("header length == 0\n");
     status = RPC_S_PROTOCOL_ERROR;
     goto fail;
   }
@@ -348,6 +350,7 @@ RPC_STATUS RPCRT4_Receive(RpcConnection *Connection, RpcPktHdr **Header,
     }
   }
   if (dwRead != hdr_length - sizeof(common_hdr)) {
+    WARN("bad header length, %ld/%ld bytes\n", dwRead, hdr_length - sizeof(common_hdr));
     status = RPC_S_PROTOCOL_ERROR;
     goto fail;
   }
@@ -363,6 +366,9 @@ RPC_STATUS RPCRT4_Receive(RpcConnection *Connection, RpcPktHdr **Header,
   default:
     pMsg->BufferLength = common_hdr.frag_len - hdr_length;
   }
+
+  TRACE("buffer length = %u\n", pMsg->BufferLength);
+
   status = I_RpcGetBuffer(pMsg);
   if (status != RPC_S_OK) goto fail;
 
@@ -388,12 +394,15 @@ RPC_STATUS RPCRT4_Receive(RpcConnection *Connection, RpcPktHdr **Header,
       }
     }
     if (dwRead != data_length) {
+      WARN("bad data length, %ld/%ld\n", dwRead, data_length);
       status = RPC_S_PROTOCOL_ERROR;
       goto fail;
     }
 
+    /* when there is no more data left, it should be the last packet */
     if (buffer_length == pMsg->BufferLength &&
         ((*Header)->common.flags & RPC_FLG_LAST) == 0) {
+      WARN("no more data left, but not last packet\n");
       status = RPC_S_PROTOCOL_ERROR;
       goto fail;
     }
@@ -580,6 +589,7 @@ RPC_STATUS WINAPI I_RpcReceive(PRPC_MESSAGE pMsg)
     status = RPC_S_CALL_FAILED; /* ? */
     goto fail;
   default:
+    WARN("bad packet type %d\n", hdr->common.ptype);
     goto fail;
   }
 
diff --git a/dlls/rpcrt4/rpcrt4.spec b/dlls/rpcrt4/rpcrt4.spec
index 7a5aa9c1fae..a7a5b9b34a3 100644
--- a/dlls/rpcrt4/rpcrt4.spec
+++ b/dlls/rpcrt4/rpcrt4.spec
@@ -72,7 +72,7 @@
 @ stub RpcGetAsyncCallStatus
 @ stub RpcIfIdVectorFree
 @ stub RpcIfInqId
-@ stub RpcImpersonateClient
+@ stdcall RpcImpersonateClient(ptr)
 @ stub RpcInitializeAsyncHandle
 @ stub RpcMgmtBindingInqParameter # win9x
 @ stub RpcMgmtBindingSetParameter # win9x