diff --git a/kernel/syscall/ipcpipe.c b/kernel/syscall/ipcpipe.c
index b8dc6de..7617528 100644
--- a/kernel/syscall/ipcpipe.c
+++ b/kernel/syscall/ipcpipe.c
@@ -49,6 +49,13 @@ int32_t SYSCALL5(sys_ipcpipe, pid1, pipenum1, cmd1, buffer1, len1) {
       }
 
       spinlock_acquire(&proc->pipes_spinlock);
+      if (proc->pipes[pipenum] != NULL) {
+        spinlock_release(&proc->pipes_spinlock);
+        ipc_pipefree(pipe);
+        dlfree(pipe);
+        ret = E_RESOURCEAVAIL;
+        goto done;
+      }
       proc->pipes[pipenum] = pipe;
       spinlock_release(&proc->pipes_spinlock);