--- a/toolkit/mozapps/update/updater/updater.cpp
+++ b/toolkit/mozapps/update/updater/updater.cpp
@@ -152,17 +152,17 @@ BOOL PathGetSiblingFilePath(LPWSTR desti
 #endif
 
 //-----------------------------------------------------------------------------
 
 // This variable lives in libbz2.  It's declared in bzlib_private.h, so we just
 // declare it here to avoid including that entire header file.
 #define BZ2_CRC32TABLE_UNDECLARED
 
-#if MOZ_IS_GCC
+#if MOZ_IS_GCC || defined(__clang__)
 extern "C"  __attribute__((visibility("default"))) unsigned int BZ2_crc32Table[256];
 #undef BZ2_CRC32TABLE_UNDECLARED
 #elif defined(__SUNPRO_C) || defined(__SUNPRO_CC)
 extern "C" __global unsigned int BZ2_crc32Table[256];
 #undef BZ2_CRC32TABLE_UNDECLARED
 #endif
 #if defined(BZ2_CRC32TABLE_UNDECLARED)
 extern "C" unsigned int BZ2_crc32Table[256];