diff --git a/makefile b/makefile
index de02d17..0bdaac5 100644
--- a/makefile
+++ b/makefile
@@ -44,6 +44,9 @@ CONDA_ENV_NAMES := \
 CONDA_ENV_PATHS := \
 	$(subst pypy,$(ENV_PREFIX)/$(PKG_NAME)_pypy,$(subst python=,$(ENV_PREFIX)/$(PKG_NAME)_py,$(subst .,,$(SUPPORTED_PYTHON_VERSIONS))))
 
+# envname/bin/python is unfortunately not always the correct
+# interpreter. In the case of pypy it is either envname/bin/pypy or
+# envname/bin/pypy3
 CONDA_ENV_BIN_PYTHON_PATHS := \
 	$(shell echo "$(CONDA_ENV_PATHS)" \
 	| sed 's!\(_py[[:digit:]]\+\)!\1/bin/python!g' \
@@ -52,7 +55,6 @@ CONDA_ENV_BIN_PYTHON_PATHS := \
 )
 
 
-
 empty :=
 literal_space := $(empty) $(empty)
 
diff --git a/src/pycalver/__main__.py b/src/pycalver/__main__.py
old mode 100644
new mode 100755