1 files changed, 3 insertions, 0 deletions
diff --git a/upb/sink.h b/upb/sink.h
index d44cb60..a50bafb 100644
--- a/upb/sink.h
+++ b/upb/sink.h
@@ -22,6 +22,7 @@
 
 #ifdef __cplusplus
 namespace upb {
+class BufferSink;
 class BufferSource;
 class BytesSink;
 class Sink;
@@ -213,6 +214,8 @@ struct upb_bufsrc {
 #endif
 };
 
+UPB_BEGIN_EXTERN_C
+
 /* A class for accumulating output string data in a flat buffer. */
 
 upb_bufsink *upb_bufsink_new(upb_env *env);