diff --git a/CMakeLists.txt b/CMakeLists.txt
index aadcb9ba1..766c83977 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -494,6 +494,8 @@ elseif(CMAKE_SYSTEM_PROCESSOR STREQUAL "mips")
   set(ARCH "generic")
 elseif(CMAKE_SYSTEM_PROCESSOR STREQUAL "ppc64le")
   set(ARCH "ppc64le")
+elseif (${CMAKE_SYSTEM_PROCESSOR} STREQUAL "riscv64")
+  set(ARCH "riscv64")
 else()
   message(FATAL_ERROR "Unknown processor:" ${CMAKE_SYSTEM_PROCESSOR})
 endif()
diff --git a/include/openssl/base.h b/include/openssl/base.h
index 4ab9eca7a..a4a91f540 100644
--- a/include/openssl/base.h
+++ b/include/openssl/base.h
@@ -118,6 +118,8 @@ extern "C" {
 #define OPENSSL_32_BIT
 #elif defined(__myriad2__)
 #define OPENSSL_32_BIT
+#elif defined(__riscv) && __riscv_xlen == 64
+#define OPENSSL_64_BIT
 #else
 // Note BoringSSL only supports standard 32-bit and 64-bit two's-complement,
 // little-endian architectures. Functions will not produce the correct answer