diff --git a/tests/checks/fds.fish b/tests/checks/fds.fish
index c2a60bb1f..de581e4b2 100644
--- a/tests/checks/fds.fish
+++ b/tests/checks/fds.fish
@@ -2,6 +2,14 @@
 
 # Check that we don't leave stray FDs.
 
+set -l fds ($helper print_fds)
+test "$fds" = "0 1 2"
+or begin
+    echo This test needs to have all fds other than 0 1 and 2 closed before running >&2
+    echo Please close the other fds and try again >&2
+    exit 1
+end
+
 $helper print_fds
 # CHECK: 0 1 2