diff --git a/bin/compile b/bin/compile
index f4a20720681ec22092362c0d47c2d49ce0781cc2..e5d4fa40d8760a4d184edb8308b0dada49af37ac 100755
--- a/bin/compile
+++ b/bin/compile
@@ -33,6 +33,12 @@ if [ "$NAME" = "Python" ]; then
   [ -f manage.py ] && [ -f settings.py ] && { echo " !     Django app must be in a package subdirectory"; exit 1; }
 fi
 
+# reject a checked-in virtualenv
+if [ -d "lib" ] || [ -d "bin" ]; then
+  echo " !     You have a virtualenv checked in. You should ignore the appropriate paths in your repo. See http://devcenter.heroku.com/articles/gitignore for more info.";
+  exit 1;
+fi
+
 # copy artifacts out of cache if exists
 mkdir -p $CACHE_DIR
 for dir in $VIRTUALENV_DIRS; do
@@ -49,7 +55,7 @@ if [ "$NAME" = "Python/Django" ]; then
   SETTINGS_FILE=$(ls **/settings.py | head -1)
   PROJECT=$(dirname $SETTINGS_FILE)
   echo "Injecting code into $SETTINGS_FILE to read from DATABASE_URL" | indent
-  
+
   cat >>$SETTINGS_FILE <<EOF
 
 import os, sys, urlparse