diff --git a/host.c b/host.c
index ec8731d..33c808a 100644
--- a/host.c
+++ b/host.c
@@ -135,6 +135,9 @@ enet_host_destroy (ENetHost * host)
 {
     ENetPeer * currentPeer;
 
+    if (host == NULL)
+      return;
+
     enet_socket_destroy (host -> socket);
 
     for (currentPeer = host -> peers;
diff --git a/packet.c b/packet.c
index fd59b14..3adb287 100644
--- a/packet.c
+++ b/packet.c
@@ -55,6 +55,9 @@ enet_packet_create (const void * data, size_t dataLength, enet_uint32 flags)
 void
 enet_packet_destroy (ENetPacket * packet)
 {
+    if (packet == NULL)
+      return;
+
     if (packet -> freeCallback != NULL)
       (* packet -> freeCallback) (packet);
     if (! (packet -> flags & ENET_PACKET_FLAG_NO_ALLOCATE) &&
diff --git a/unix.c b/unix.c
index a225b57..c421b7e 100644
--- a/unix.c
+++ b/unix.c
@@ -273,7 +273,8 @@ enet_socket_accept (ENetSocket socket, ENetAddress * address)
 void
 enet_socket_destroy (ENetSocket socket)
 {
-    close (socket);
+    if (socket != -1)
+      close (socket);
 }
 
 int
diff --git a/win32.c b/win32.c
index 0a213e7..708d306 100644
--- a/win32.c
+++ b/win32.c
@@ -220,7 +220,8 @@ enet_socket_accept (ENetSocket socket, ENetAddress * address)
 void
 enet_socket_destroy (ENetSocket socket)
 {
-    closesocket (socket);
+    if (socket != INVALID_SOCKET)
+      closesocket (socket);
 }
 
 int