diff --git a/base/include/android-base/file.h b/base/include/android-base/file.h
index af14892..667d6fb 100644
--- a/base/include/android-base/file.h
+++ b/base/include/android-base/file.h
@@ -18,12 +18,18 @@
 #define ANDROID_BASE_FILE_H
 
 #include <sys/stat.h>
+#include <sys/types.h>
 #include <string>
 
 #if !defined(_WIN32) && !defined(O_BINARY)
 #define O_BINARY 0
 #endif
 
+#if defined(__APPLE__)
+/* Mac OS has always had a 64-bit off_t, so it doesn't have off64_t. */
+typedef off_t off64_t;
+#endif
+
 namespace android {
 namespace base {