diff --git a/loader/src/common/daemon.c b/loader/src/common/daemon.c
index 9910ef1..cf8ef5a 100644
--- a/loader/src/common/daemon.c
+++ b/loader/src/common/daemon.c
@@ -342,6 +342,14 @@ bool rezygiskd_update_mns(enum mount_namespace_state nms_state, char *buf, size_
     return false;
   }
 
+  if (target_fd == 0) {
+    LOGE("Failed to get target fd");
+
+    close(fd);
+
+    return false;
+  }
+
   snprintf(buf, buf_size, "/proc/%u/fd/%u", target_pid, target_fd);
 
   close(fd);
diff --git a/zygiskd/src/zygiskd.c b/zygiskd/src/zygiskd.c
index 4fb02c0..1eac1c9 100644
--- a/zygiskd/src/zygiskd.c
+++ b/zygiskd/src/zygiskd.c
@@ -647,8 +647,17 @@ void zygiskd_start(char *restrict argv[]) {
           save_mns_fd(pid, Module, impl);
         }
 
-        uint32_t clean_namespace_fd = (uint32_t)save_mns_fd(pid, (enum MountNamespaceState)mns_state, impl);
-        ret = write_uint32_t(client_fd, clean_namespace_fd);
+        int clean_namespace_fd = save_mns_fd(pid, (enum MountNamespaceState)mns_state, impl);
+        if (clean_namespace_fd == -1) {
+          LOGE("Failed to save mount namespace fd for pid %d: %s\n", pid, strerror(errno));
+
+          ret = write_uint32_t(client_fd, (uint32_t)0);
+          ASSURE_SIZE_WRITE_BREAK("UpdateMountNamespace", "clean_namespace_fd", ret, sizeof(clean_namespace_fd));
+
+          break;
+        }
+
+        ret = write_uint32_t(client_fd, (uint32_t)clean_namespace_fd);
         ASSURE_SIZE_WRITE_BREAK("UpdateMountNamespace", "clean_namespace_fd", ret, sizeof(clean_namespace_fd));
 
         break;