diff --git a/dlls/ws2_32/socket.c b/dlls/ws2_32/socket.c
index fac090d6edb..c606659822f 100644
--- a/dlls/ws2_32/socket.c
+++ b/dlls/ws2_32/socket.c
@@ -2319,6 +2319,13 @@ static BOOL WINAPI WS2_AcceptEx(SOCKET listener, SOCKET acceptor, PVOID dest, DW
         return FALSE;
     }
 
+    if ((local_addr_len < sizeof(struct sockaddr_in) + 16)
+       || (rem_addr_len < sizeof(struct sockaddr_in) + 16))
+    {
+        SetLastError(WSAEINVAL);
+        return FALSE;
+    }
+
     fd = get_sock_fd( listener, FILE_READ_DATA, NULL );
     if (fd == -1)
     {
diff --git a/dlls/ws2_32/tests/sock.c b/dlls/ws2_32/tests/sock.c
index c1d69569798..343fd9474ae 100644
--- a/dlls/ws2_32/tests/sock.c
+++ b/dlls/ws2_32/tests/sock.c
@@ -5348,12 +5348,22 @@ static void test_AcceptEx(void)
 
     bret = pAcceptEx(listener, acceptor, buffer, 0, 0, sizeof(struct sockaddr_in) + 16,
         &bytesReturned, &overlapped);
-    todo_wine ok(bret == FALSE && WSAGetLastError() == WSAEINVAL, "AcceptEx on too small local address size "
+    ok(bret == FALSE && WSAGetLastError() == WSAEINVAL, "AcceptEx on too small local address size "
+        "returned %d + errno %d\n", bret, WSAGetLastError());
+
+    bret = pAcceptEx(listener, acceptor, buffer, 0, sizeof(struct sockaddr_in) + 15,
+        sizeof(struct sockaddr_in) + 16, &bytesReturned, &overlapped);
+    ok(bret == FALSE && WSAGetLastError() == WSAEINVAL, "AcceptEx on too small local address size "
         "returned %d + errno %d\n", bret, WSAGetLastError());
 
     bret = pAcceptEx(listener, acceptor, buffer, 0, sizeof(struct sockaddr_in) + 16, 0,
         &bytesReturned, &overlapped);
-    todo_wine ok(bret == FALSE && WSAGetLastError() == WSAEINVAL, "AcceptEx on too small remote address size "
+    ok(bret == FALSE && WSAGetLastError() == WSAEINVAL, "AcceptEx on too small remote address size "
+        "returned %d + errno %d\n", bret, WSAGetLastError());
+
+    bret = pAcceptEx(listener, acceptor, buffer, 0, sizeof(struct sockaddr_in) + 16,
+        sizeof(struct sockaddr_in) + 15, &bytesReturned, &overlapped);
+    ok(bret == FALSE && WSAGetLastError() == WSAEINVAL, "AcceptEx on too small remote address size "
         "returned %d + errno %d\n", bret, WSAGetLastError());
 
     bret = pAcceptEx(listener, acceptor, buffer, 0,
@@ -5362,6 +5372,10 @@ static void test_AcceptEx(void)
     ok(bret == FALSE && WSAGetLastError() == ERROR_INVALID_PARAMETER, "AcceptEx on a NULL overlapped "
         "returned %d + errno %d\n", bret, WSAGetLastError());
 
+    bret = pAcceptEx(listener, acceptor, buffer, 0, 0, 0, &bytesReturned, NULL);
+    ok(bret == FALSE && WSAGetLastError() == ERROR_INVALID_PARAMETER, "AcceptEx on a NULL overlapped "
+        "returned %d + errno %d\n", bret, WSAGetLastError());
+
     bret = pAcceptEx(listener, acceptor, buffer, sizeof(buffer) - 2*(sizeof(struct sockaddr_in) + 16),
         sizeof(struct sockaddr_in) + 16, sizeof(struct sockaddr_in) + 16,
         &bytesReturned, &overlapped);