diff --git a/test/100-sed-autoconf-basename.sh b/test/100-sed-autoconf-basename.sh
index ddd8ea5..a69a94b 100644
--- a/test/100-sed-autoconf-basename.sh
+++ b/test/100-sed-autoconf-basename.sh
@@ -1,15 +1 @@
-basename='/^.*\/\([^/][^/]*\)\/*$/{
-	    s//\1/
-	    q
-	  }
-  /^X\/\(\/\/\)$/{
-	    s//\1/
-	    q
-  }
-  /^X\/\(\/\).*/{
-	    s//\1/
-	    q
-  }
-  s/.*/./; q'
-
-echo 'X/foo/bar' | \sed "$basename"
+echo 'X/foo/bar' | \sed -f test/data/basename.sed
diff --git a/test/data/basename.sed b/test/data/basename.sed
new file mode 100644
index 0000000..86b8772
--- /dev/null
+++ b/test/data/basename.sed
@@ -0,0 +1,13 @@
+/^.*\/\([^/][^/]*\)\/*$/{
+	    s//\1/
+	    q
+	  }
+  /^X\/\(\/\/\)$/{
+	    s//\1/
+	    q
+  }
+  /^X\/\(\/\).*/{
+	    s//\1/
+	    q
+  }
+  s/.*/./; q