diff --git a/source/checksum.c b/source/checksum.c
index 6e50e57..84b5a42 100644
--- a/source/checksum.c
+++ b/source/checksum.c
@@ -18,7 +18,13 @@ Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 
 */
 #ifdef HAVE_CONFIG_H
-# include <config.h>
+# include "config.h"
+#endif
+#ifdef HAVE_STRING_H
+#include <string.h>
+#endif
+#ifdef HAVE_STRINGS_H
+#include <strings.h>
 #endif
 #include "checksum.h"
 #include "crc.h"