--- a/configure.ac
+++ b/configure.ac
@@ -25,8 +25,7 @@
 # Checks for header files.
 AC_HEADER_STDC
 AC_CHECK_HEADERS([netinet/in.h stdint.h stdlib.h sys/time.h])
-CPPFLAGS="$CPPFLAGS -I/usr/include/cdk"
-AC_CHECK_HEADERS([cdk/cdk.h],,[
+AC_CHECK_HEADERS([cdk.h],,[
 	echo 'cdk version >= 5.0 and includes (developer-version) required'
 	exit 1
 	])