diff --git a/coverage.sh b/coverage.sh
index 2437302..5b8faab 100755
--- a/coverage.sh
+++ b/coverage.sh
@@ -1,9 +1,11 @@
 #!/bin/bash
 
-# you must install coverage before executing this script
-#   pip install coverage
-
 . env/bin/activate
 
+which coverage >/dev/null 2>&1
+if [ "$?" -ne 0 ]; then
+  pip install coverage
+fi
+
 coverage run manage.py test
 coverage report