diff --git a/apr-api-docs.spec b/apr-api-docs.spec
index 1418ca5..f5f3724 100644
--- a/apr-api-docs.spec
+++ b/apr-api-docs.spec
@@ -29,8 +29,7 @@ cp %{SOURCE0} doxygen.conf
 
 %build
 cd %{name}-%{version}
-%define docheaders %(ls %{_includedir}/apr-1/*.h | xargs echo)
-sed -e 's,\(INPUT *= *\).*$,\1%{docheaders},' \
+sed -e 's,\(INPUT *= *\).*$,\1%{_includedir}/apr-1,' \
     -e 's,\(OUTPUT_DIRECTORY *= *\).*$,\1docs,' \
     -e 's,\(GENERATE_TAGFILE *= *\).*$,\1docs/apr.tag,' \
 doxygen.conf | doxygen -