diff --git a/sys/shm/shmpipe.c b/sys/shm/shmpipe.c
index 6465e381c0..38711f9f3c 100644
--- a/sys/shm/shmpipe.c
+++ b/sys/shm/shmpipe.c
@@ -262,7 +262,7 @@ static ShmArea *
 sp_open_shm (char *path, int id, mode_t perms, size_t size)
 {
   ShmArea *area = spalloc_new (ShmArea);
-  char tmppath[PATH_MAX];
+  char tmppath[32];
   int flags;
   int prot;
   int i = 0;
@@ -285,7 +285,7 @@ sp_open_shm (char *path, int id, mode_t perms, size_t size)
     area->shm_fd = shm_open (path, flags, perms);
   } else {
     do {
-      snprintf (tmppath, PATH_MAX, "/shmpipe.5%d.%5d", getpid (), i++);
+      snprintf (tmppath, sizeof (tmppath), "/shmpipe.%5d.%5d", getpid (), i++);
       area->shm_fd = shm_open (tmppath, flags, perms);
     } while (area->shm_fd < 0 && errno == EEXIST);
   }