diff --git a/README.md b/README.md
index c22b3f5..deb2938 100644
--- a/README.md
+++ b/README.md
@@ -1067,10 +1067,9 @@ Alternative to the `dirname` command.
 dirname() {
     # Usage: dirname "path"
     dir=${1%%/}
+    [[ "${dir##*/*}" ]] && dir=.
     dir=${dir%/*}
 
-    [[ $1 == */* ]] || dir=.
-
     printf '%s\n' "${dir:-/}"
 }
 ```
diff --git a/manuscript/chapter5.txt b/manuscript/chapter5.txt
index 84b9e2b..e602a67 100644
--- a/manuscript/chapter5.txt
+++ b/manuscript/chapter5.txt
@@ -10,10 +10,9 @@ Alternative to the `dirname` command.
 dirname() {
     # Usage: dirname "path"
     dir=${1%%/}
+    [[ "${dir##*/*}" ]] && dir=.
     dir=${dir%/*}
 
-    [[ $1 == */* ]] || dir=.
-
     printf '%s\n' "${dir:-/}"
 }
 ```
diff --git a/test.sh b/test.sh
index debf2da..597de2b 100755
--- a/test.sh
+++ b/test.sh
@@ -129,6 +129,9 @@ test_dirname() {
 
     result="$(dirname "/foo/foo")"
     assert_equals "$result" "/foo"
+
+    result="$(dirname "something/")"
+    assert_equals "$result" "."
 }
 
 test_basename() {