diff --git a/rtc_base/system/arch.h b/rtc_base/system/arch.h
index be2367b85f..e00150b65f 100644
--- a/rtc_base/system/arch.h
+++ b/rtc_base/system/arch.h
@@ -79,6 +79,9 @@
 #elif defined(__EMSCRIPTEN__)
 #define WEBRTC_ARCH_32_BITS
 #define WEBRTC_ARCH_LITTLE_ENDIAN
+#elif defined(_M_IA64) || defined(__ia64__) || defined(__ia64)
+#define WEBRTC_ARCH_64_BITS
+#define WEBRTC_ARCH_LITTLE_ENDIAN
 #else
 #error Please add support for your architecture in rtc_base/system/arch.h
 #endif