diff --git a/include/polarssl/sha1.h b/include/polarssl/sha1.h
index 0d5e67e..a512edd 100644
--- a/include/polarssl/sha1.h
+++ b/include/polarssl/sha1.h
@@ -145,6 +145,9 @@
  */
 int sha1_self_test( int verbose );
 
+/* Internal use */
+void sha1_process( sha1_context *ctx, const unsigned char data[64] );
+
 #ifdef __cplusplus
 }
 #endif