diff --git a/share/functions/fish_fletcher16.fish b/share/functions/fish_fletcher16.fish
new file mode 100644
index 000000000..beaf8cb20
--- /dev/null
+++ b/share/functions/fish_fletcher16.fish
@@ -0,0 +1,10 @@
+function fish_fletcher16 --argument input -d "compute a fletcher 16 checksum"
+    set -l sum1 0
+    set -l sum2 0
+    for char in (string split '' $input)
+        set -l ordinal (printf %2u "'$char")
+        math "($sum1 + $ordinal)" % 255 | read sum1
+        math "($sum2 + $sum1)" % 255 | read sum2
+    end
+    math "bitor $sum1,$(math $sum2 '*' pow 2,8)"
+end