diff --git a/src/hb-ucdn.cc b/src/hb-ucdn.cc
index ed26ba2d1..35063043f 100644
--- a/src/hb-ucdn.cc
+++ b/src/hb-ucdn.cc
@@ -18,9 +18,7 @@
 
 #include "hb-unicode-private.hh"
 
-HB_BEGIN_DECLS
 #include "ucdn.h"
-HB_END_DECLS
 
 static const hb_script_t ucdn_script_translate[] =
 {
diff --git a/src/hb-ucdn/ucdn.h b/src/hb-ucdn/ucdn.h
index 7fba6153d..802f044a8 100644
--- a/src/hb-ucdn/ucdn.h
+++ b/src/hb-ucdn/ucdn.h
@@ -17,6 +17,23 @@
 #ifndef UCDN_H
 #define UCDN_H
 
+#if defined(__GNUC__) && (__GNUC__ >= 4) && !defined(__MINGW32__)
+# define HB_BEGIN_VISIBILITY _Pragma ("GCC visibility push(hidden)")
+# define HB_END_VISIBILITY _Pragma ("GCC visibility pop")
+#else
+# define HB_BEGIN_VISIBILITY
+# define HB_END_VISIBILITY
+#endif
+#ifdef __cplusplus
+# define HB_BEGIN_HEADER  extern "C" { HB_BEGIN_VISIBILITY
+# define HB_END_HEADER  HB_END_VISIBILITY }
+#else
+# define HB_BEGIN_HEADER  HB_BEGIN_VISIBILITY
+# define HB_END_HEADER  HB_END_VISIBILITY
+#endif
+
+HB_BEGIN_HEADER
+
 #include <stdint.h>
 
 #define UCDN_EAST_ASIAN_F 0
@@ -287,4 +304,6 @@ int ucdn_compat_decompose(uint32_t code, uint32_t *decomposed);
  */
 int ucdn_compose(uint32_t *code, uint32_t a, uint32_t b);
 
+HB_END_HEADER
+
 #endif