diff --git a/share/completions/git.fish b/share/completions/git.fish
index f33464011..5ce892abb 100644
--- a/share/completions/git.fish
+++ b/share/completions/git.fish
@@ -1119,7 +1119,7 @@ end
 
 ### difftool
 complete -c git -n __fish_git_needs_command -a difftool -d 'Open diffs in a visual tool'
-complete -c git -n '__fish_git_using_command difftool' -k -a '(__fish_git_ranges)'
+complete -c git -n '__fish_git_using_command difftool; and not contains -- -- (commandline -opc)' -k -a '(__fish_git_ranges)'
 complete -c git -n '__fish_git_using_command difftool' -l cached -d 'Visually show diff of changes in the index'
 complete -f -c git -n '__fish_git_using_command difftool' -a '(__fish_git_files modified deleted modified-staged-deleted)'
 complete -f -c git -n '__fish_git_using_command difftool' -s g -l gui -d 'Use `diff.guitool` instead of `diff.tool`'