diff --git a/rtc_base/system/arch.h b/rtc_base/system/arch.h
index ed216e6..be2367b 100644
--- a/rtc_base/system/arch.h
+++ b/rtc_base/system/arch.h
@@ -15,8 +15,9 @@
 #define RTC_BASE_SYSTEM_ARCH_H_
 
 // Processor architecture detection.  For more info on what's defined, see:
-//   http://msdn.microsoft.com/en-us/library/b0084kay.aspx
-//   http://www.agner.org/optimize/calling_conventions.pdf
+//   https://docs.microsoft.com/en-us/cpp/preprocessor/predefined-macros
+//   https://www.agner.org/optimize/calling_conventions.pdf
+//   https://sourceforge.net/p/predef/wiki/Architectures/
 //   or with gcc, run: "echo | gcc -E -dM -"
 #if defined(_M_X64) || defined(__x86_64__)
 #define WEBRTC_ARCH_X86_FAMILY
@@ -32,17 +33,45 @@
 #define WEBRTC_ARCH_X86
 #define WEBRTC_ARCH_32_BITS
 #define WEBRTC_ARCH_LITTLE_ENDIAN
-#elif defined(__ARMEL__)
+#elif defined(_M_ARM) || defined(__ARMEL__)
 #define WEBRTC_ARCH_ARM_FAMILY
 #define WEBRTC_ARCH_32_BITS
 #define WEBRTC_ARCH_LITTLE_ENDIAN
-#elif defined(__MIPSEL__)
+#elif defined(__MIPSEL__) || defined(__MIPSEB__)
 #define WEBRTC_ARCH_MIPS_FAMILY
 #if defined(__LP64__)
 #define WEBRTC_ARCH_64_BITS
 #else
 #define WEBRTC_ARCH_32_BITS
 #endif
+#if defined(__MIPSEL__)
+#define WEBRTC_ARCH_LITTLE_ENDIAN
+#else
+#define WEBRTC_ARCH_BIG_ENDIAN
+#endif
+#elif defined(__PPC__)
+#if defined(__PPC64__)
+#define WEBRTC_ARCH_64_BITS
+#else
+#define WEBRTC_ARCH_32_BITS
+#endif
+#if defined(__LITTLE_ENDIAN__)
+#define WEBRTC_ARCH_LITTLE_ENDIAN
+#else
+#define WEBRTC_ARCH_BIG_ENDIAN
+#endif
+#elif defined(__sparc) || defined(__sparc__)
+#if __SIZEOF_LONG__ == 8
+#define WEBRTC_ARCH_64_BITS
+#else
+#define WEBRTC_ARCH_32_BITS
+#endif
+#define WEBRTC_ARCH_BIG_ENDIAN
+#elif defined(__riscv) && __riscv_xlen == 64
+#define WEBRTC_ARCH_64_BITS
+#define WEBRTC_ARCH_LITTLE_ENDIAN
+#elif defined(__riscv) && __riscv_xlen == 32
+#define WEBRTC_ARCH_32_BITS
 #define WEBRTC_ARCH_LITTLE_ENDIAN
 #elif defined(__pnacl__)
 #define WEBRTC_ARCH_32_BITS