diff --git a/gfx/ots/include/opentype-sanitiser.h b/gfx/ots/include/opentype-sanitiser.h
--- a/gfx/ots/include/opentype-sanitiser.h
+++ b/gfx/ots/include/opentype-sanitiser.h
@@ -1,15 +1,35 @@
 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef OPENTYPE_SANITISER_H_
 #define OPENTYPE_SANITISER_H_
 
+#if defined(_WIN32) || defined(__CYGWIN__)
+  #define OTS_DLL_IMPORT __declspec(dllimport)
+  #define OTS_DLL_EXPORT __declspec(dllexport)
+#else
+  #if __GNUC__ >= 4
+    #define OTS_DLL_IMPORT __attribute__((visibility ("default")))
+    #define OTS_DLL_EXPORT __attribute__((visibility ("default")))
+  #endif
+#endif
+
+#ifdef OTS_DLL
+  #ifdef OTS_DLL_EXPORTS
+    #define OTS_API OTS_DLL_EXPORT
+  #else
+    #define OTS_API OTS_DLL_IMPORT
+  #endif
+#else
+  #define OTS_API
+#endif
+
 #if defined(_WIN32)
 #include <stdlib.h>
 typedef signed char int8_t;
 typedef unsigned char uint8_t;
 typedef short int16_t;
 typedef unsigned short uint16_t;
 typedef int int32_t;
 typedef unsigned int uint32_t;
@@ -178,18 +198,18 @@ class OTSStream {
 // Process a given OpenType file and write out a sanitised version
 //   output: a pointer to an object implementing the OTSStream interface. The
 //     sanitisied output will be written to this. In the even of a failure,
 //     partial output may have been written.
 //   input: the OpenType file
 //   length: the size, in bytes, of |input|
 //   preserve_graphite_tables: whether to preserve Graphite Layout tables
 // -----------------------------------------------------------------------------
-bool Process(OTSStream *output, const uint8_t *input, size_t length,
-             bool preserve_graphite_tables = false);
+bool OTS_API Process(OTSStream *output, const uint8_t *input, size_t length,
+                     bool preserve_graphite_tables = false);
 
 // Force to disable debug output even when the library is compiled with
 // -DOTS_DEBUG.
 void DisableDebugOutput();
 
 }  // namespace ots
 
 #endif  // OPENTYPE_SANITISER_H_