diff --git a/17-introspective/tf-17.py b/17-introspective/tf-17.py
old mode 100644
new mode 100755
diff --git a/18-reflective/tf-18.py b/18-reflective/tf-18.py
old mode 100644
new mode 100755
diff --git a/README.md b/README.md
index 2c86e81..238c08d 100644
--- a/README.md
+++ b/README.md
@@ -1,12 +1,14 @@
 Exercises in Programming Style
 ==============================
 
-Comprehensive collection of well-known, and not so well-known, programming styles using a simple computational task, term frequency.
+Comprehensive collection of well-known, and not so well-known, programming
+styles using a simple computational task, term frequency.
 
 Additions are welcome! 
 
 You can contribute: 
-- an example program that follows one of the existing styles, but written in a different programming language 
+- an example program that follows one of the existing styles, but written in a
+  different programming language 
 - an entirely new programming style
 - new names for the existing styles
 - discussion of names, pros and cons of each style
@@ -32,6 +34,14 @@ should not be here)
 Contributions of new names and discussion should be done under Issues
 or on the Wiki part of this repo.
 
+To test your work, make sure your script is executable and then run:
+
+```
+./test/test.sh NN
+```
+
+Where `NN` is the number prefix of the directory you're adding.
+
 Never stop exercising!
 
 Love,
diff --git a/test/test.sh b/test/test.sh
index ff7d1c9..1cf2753 100755
--- a/test/test.sh
+++ b/test/test.sh
@@ -4,11 +4,21 @@ function msg() {
     echo $(date +%T) "$@"
 }
 
+# Move to a predictable place.
+cd $(dirname $0)
+
 failures=0
 total=0
-mydir=$(cd $(dirname $0); pwd)
+mydir=$(pwd)
+if [ -z "$1" ]; then
+    styles_to_test=$(echo ../[0-9][0-9]-*)
+else
+    styles_to_test=../$1-*
+fi
+
 files=$(echo *.txt)
-for dir in ../[0-9][0-9]-* ; do
+
+for dir in $styles_to_test ; do
     cd $dir
     for file in $files ; do
         for exe in * ; do