diff --git a/reactos/lib/drivers/ip/network/arp.c b/reactos/lib/drivers/ip/network/arp.c
index 1ac2d5baaef..5c830589ca8 100644
--- a/reactos/lib/drivers/ip/network/arp.c
+++ b/reactos/lib/drivers/ip/network/arp.c
@@ -150,6 +150,8 @@ BOOLEAN ARPTransmit(PIP_ADDRESS Address, PIP_INTERFACE Interface)
         &Address->Address,               /* Target's (remote) protocol address */
         ARP_OPCODE_REQUEST);             /* ARP request */
 
+    if( !NdisPacket ) return FALSE;
+
     ASSERT_KM_POINTER(NdisPacket);
     ASSERT_KM_POINTER(PC(NdisPacket));
     PC(NdisPacket)->DLComplete = ARPTransmitComplete;
diff --git a/reactos/lib/drivers/ip/transport/rawip/rawip.c b/reactos/lib/drivers/ip/transport/rawip/rawip.c
index 5422b17d131..90f0ac7b775 100644
--- a/reactos/lib/drivers/ip/transport/rawip/rawip.c
+++ b/reactos/lib/drivers/ip/transport/rawip/rawip.c
@@ -143,6 +143,13 @@ NTSTATUS BuildRawIpPacket(
 	break;
     }
 
+    if( !NT_SUCCESS(Status) ) {
+	TI_DbgPrint(MIN_TRACE, ("Cannot add header. Status = (0x%X)\n",
+				Status));
+	FreeNdisPacket(Packet->NdisPacket);
+	return Status;
+    }
+
     TI_DbgPrint(MID_TRACE, ("Copying data (hdr %x data %x (%d))\n",
 			    Packet->Header, Packet->Data,
 			    (PCHAR)Packet->Data - (PCHAR)Packet->Header));
diff --git a/reactos/lib/drivers/ip/transport/tcp/if.c b/reactos/lib/drivers/ip/transport/tcp/if.c
index 9821d367dfe..225215e31f7 100644
--- a/reactos/lib/drivers/ip/transport/tcp/if.c
+++ b/reactos/lib/drivers/ip/transport/tcp/if.c
@@ -34,9 +34,9 @@ PVOID TCPPrepareInterface( PIP_INTERFACE IF ) {
     NTSTATUS Status;
     POSK_IFADDR ifaddr = exAllocatePool
 	( NonPagedPool, sizeof(*ifaddr) + 2 * sizeof( struct sockaddr_in ) );
+    if( !ifaddr ) return NULL;
     struct sockaddr_in *addr_in = (struct sockaddr_in *)&ifaddr[1];
     struct sockaddr_in *dstaddr_in = (struct sockaddr_in *)&addr_in[1];
-    if( !ifaddr ) return NULL;
 
     TI_DbgPrint(DEBUG_TCPIF,("Called\n"));
 
diff --git a/reactos/lib/drivers/ip/transport/udp/udp.c b/reactos/lib/drivers/ip/transport/udp/udp.c
index 07561d44036..1dba3035179 100644
--- a/reactos/lib/drivers/ip/transport/udp/udp.c
+++ b/reactos/lib/drivers/ip/transport/udp/udp.c
@@ -330,6 +330,8 @@ NTSTATUS UDPShutdown(
   /* Deregister this protocol with IP layer */
   IPRegisterProtocol(IPPROTO_UDP, NULL);
 
+  UDPInitialized = FALSE;
+
   return STATUS_SUCCESS;
 }