diff --git a/bin/git-authors.sh b/bin/git-authors.sh
index 3383558..709dacb 100755
--- a/bin/git-authors.sh
+++ b/bin/git-authors.sh
@@ -1,5 +1,8 @@
 #!/bin/sh
 
+# Enforce being in a git repository
+git rev-parse --is-inside-work-tree >/dev/null || exit $?
+
 # save as i.e.: git-authors and set the executable flag
 git ls-tree -r -z --name-only HEAD -- "${1}" \
   | xargs -0 -n1 git blame --line-porcelain HEAD \
@@ -7,4 +10,3 @@ git ls-tree -r -z --name-only HEAD -- "${1}" \
   | sort \
   | uniq -c \
   | sort -nr
-