diff --git a/share/completions/docker.fish b/share/completions/docker.fish
index 16bfc628a..df0a5dab5 100644
--- a/share/completions/docker.fish
+++ b/share/completions/docker.fish
@@ -1 +1,4 @@
-docker completion fish 2>/dev/null | source
+# In WSL, when the docker app is not yet started, "docker" is a script printing
+# some error message on stdout instead of a sourceable script
+set -l docker_completion "$(docker completion fish 2>/dev/null)"
+and eval "$docker_completion"