diff --git a/python-zmq.spec b/python-zmq.spec
index 4f13440..9819eb0 100644
--- a/python-zmq.spec
+++ b/python-zmq.spec
@@ -99,19 +99,19 @@ This package contains the test suite for the Python bindings.
 
 
 %prep
-%setup -q -n pyzmq-%{version}
+%autosetup -p1 -n pyzmq-%{version}
 
 # remove bundled libraries
 rm -rv bundled/
 
-# remove the Cython .c files in order to regenerate them:
-find zmq -name "*.c" -delete
+# Remove any Cython-generated .c files in order to regenerate them:
+find zmq -name '*.c' -print -delete
 
-# remove shebangs
-grep -lr "^#\!/usr/bin/env python" | xargs sed -i "1d"
-
-# remove excecutable bits
-find . -type f -executable | xargs chmod -x
+# Remove shebangs from non-script sources. The find-then-modify pattern
+# preserves mtimes on sources that did not need to be modified.
+find 'src' -type f -name '*.py' \
+    -exec gawk '/^#!/ { print FILENAME }; { nextfile }' '{}' '+' |
+  xargs -r sed -r -i '1{/^#!/d}'
 
 # BUG: A file is licensed Apache-2.0, but the license text is not distributed
 # https://github.com/zeromq/pyzmq/issues/2048