diff --git a/bin/doctest.sh b/bin/doctest.sh
index 8aaa7f7..0b37314 100755
--- a/bin/doctest.sh
+++ b/bin/doctest.sh
@@ -2,4 +2,4 @@
 
 cd $(dirname "$0")
 cd ..
-python -m doctest -o ELLIPSIS /dev/stdin < jplephem/__init__.py
+python3 -m doctest -o ELLIPSIS /dev/stdin < jplephem/__init__.py