diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index 9147fba3d5..f68c8e0646 100644
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash
@@ -1691,6 +1691,10 @@ __git_diff_common_options="--stat --numstat --shortstat --summary
 			--textconv --no-textconv
 "
 
+__git_diff_difftool_options="--cached --staged --pickaxe-all --pickaxe-regex
+			--base --ours --theirs --no-index --relative
+			$__git_diff_common_options"
+
 _git_diff ()
 {
 	__git_has_doubledash && return
@@ -1713,10 +1717,7 @@ _git_diff ()
 		return
 		;;
 	--*)
-		__gitcomp "--cached --staged --pickaxe-all --pickaxe-regex
-			--base --ours --theirs --no-index
-			$__git_diff_common_options
-			"
+		__gitcomp "$__git_diff_difftool_options"
 		return
 		;;
 	esac
@@ -1738,11 +1739,7 @@ _git_difftool ()
 		return
 		;;
 	--*)
-		__gitcomp_builtin difftool "$__git_diff_common_options
-					--base --cached --ours --theirs
-					--pickaxe-all --pickaxe-regex
-					--relative --staged
-					"
+		__gitcomp_builtin difftool "$__git_diff_difftool_options"
 		return
 		;;
 	esac