diff --git a/share/completions/mount.fish b/share/completions/mount.fish
index ba0d985fc..9375a473e 100644
--- a/share/completions/mount.fish
+++ b/share/completions/mount.fish
@@ -1,12 +1,4 @@
 # Completions for mount
-function __fish_complete_blockdevice
-	set -l cmd (commandline -ct)
-	[ "" = "$cmd" ]; and return
-	for f in $cmd*
-		[ -b $f ]; and printf "%s\t%s\n" $f "Block device"
-		[ -d $f ]; and printf "%s\n" $f/
-	end
-end
 
 complete -x -c mount -a '(__fish_complete_blockdevice)'
 # In case `mount UUID=` and similar also works
diff --git a/share/functions/__fish_complete_blockdevice.fish b/share/functions/__fish_complete_blockdevice.fish
new file mode 100644
index 000000000..d07487dec
--- /dev/null
+++ b/share/functions/__fish_complete_blockdevice.fish
@@ -0,0 +1,12 @@
+# Helper function for completions that need to enumerate block devices.
+function __fish_complete_blockdevice
+    set -l cmd (commandline -ct)
+    test "" = "$cmd"
+    and return
+    for f in $cmd*
+        test -b $f
+        and printf "%s\t%s\n" $f "Block device"
+        test -d $f
+        and printf "%s\n" $f/
+    end
+end