diff --git a/include/polarssl/sha4.h b/include/polarssl/sha4.h
index 6aae124..5563676 100644
--- a/include/polarssl/sha4.h
+++ b/include/polarssl/sha4.h
@@ -161,6 +161,9 @@
  */
 int sha4_self_test( int verbose );
 
+/* Internal use */
+void sha4_process( sha4_context *ctx, const unsigned char data[128] );
+
 #ifdef __cplusplus
 }
 #endif