diff --git a/configure.ac.tpl b/configure.ac.tpl
index ab06402..4c2b751 100644
--- a/configure.ac.tpl
+++ b/configure.ac.tpl
@@ -113,4 +113,4 @@ AC_CONFIG_FILES([
 
 AC_OUTPUT
 
-DISTCLEANFILES += *.pc
+DISTCLEANFILES = *.pc