diff --git a/share/completions/diff.fish b/share/completions/diff.fish
index 36ceec03d..7617871e2 100644
--- a/share/completions/diff.fish
+++ b/share/completions/diff.fish
@@ -12,8 +12,8 @@ complete -c diff -s r -l recursive -d "Recursively compare subdirectories"
 complete -c diff -s N -l new-file -d "Treat absent files as empty"
 complete -c diff -s C -l context -x -d "Output NUM lines of copied context"
 complete -c diff -s c -d "Output 3 lines of copied context"
-complete -c diff -s U -l unified -x -d "Output NUM lines of unified context"
-complete -c diff -s u -d "Output 3 lines of unified context"
+complete -c diff -s U -x -d "Output NUM lines of unified context"
+complete -c diff -s u -l unified -d "Output NUM lines of unified context (default 3)"
 complete -c diff -s q -l brief -d "Output only whether the files differ"
 complete -c diff -l normal -d "Output a normal diff"
 complete -c diff -s y -l side-by-side -d "Output in two columns"