diff --git a/release_to_pypi.sh b/release_to_pypi.sh
index 4a7cb31..35358af 100755
--- a/release_to_pypi.sh
+++ b/release_to_pypi.sh
@@ -3,9 +3,17 @@
 # remove everything in the current dist/ directory
 [ -d dist ] && rm -Rfv dist
 
+# start with a clean build directory
+rm -Rfv build/
+
+# Python 2.5 doesn't support wheels
+python2.5 setup.py bdist_egg
+rm -Rfv build/
+
 for ver in 2.7 3.4; do
     python$ver setup.py bdist_egg
     python$ver setup.py bdist_wheel
+    rm -Rfv build/
 done
 
 read -p "Upload to PyPI? [y/n/x] " yesno || exit 1