diff --git a/src/backend_x64/block_of_code.cpp b/src/backend_x64/block_of_code.cpp
index b7c4035f..0d31966b 100644
--- a/src/backend_x64/block_of_code.cpp
+++ b/src/backend_x64/block_of_code.cpp
@@ -29,6 +29,8 @@ const Xbyak::Reg64 BlockOfCode::ABI_PARAM1 = Xbyak::util::rdi;
 const Xbyak::Reg64 BlockOfCode::ABI_PARAM2 = Xbyak::util::rsi;
 const Xbyak::Reg64 BlockOfCode::ABI_PARAM3 = Xbyak::util::rdx;
 const Xbyak::Reg64 BlockOfCode::ABI_PARAM4 = Xbyak::util::rcx;
+const Xbyak::Reg64 BlockOfCode::ABI_PARAM5 = Xbyak::util::r8;
+const Xbyak::Reg64 BlockOfCode::ABI_PARAM6 = Xbyak::util::r9;
 #endif
 
 constexpr size_t TOTAL_CODE_SIZE = 128 * 1024 * 1024;
diff --git a/src/backend_x64/block_of_code.h b/src/backend_x64/block_of_code.h
index 95a247e3..7164dc5b 100644
--- a/src/backend_x64/block_of_code.h
+++ b/src/backend_x64/block_of_code.h
@@ -108,6 +108,10 @@ public:
     static const Xbyak::Reg64 ABI_PARAM2;
     static const Xbyak::Reg64 ABI_PARAM3;
     static const Xbyak::Reg64 ABI_PARAM4;
+#ifndef _WIN32
+    static const Xbyak::Reg64 ABI_PARAM5;
+    static const Xbyak::Reg64 ABI_PARAM6;
+#endif
 
     bool DoesCpuSupport(Xbyak::util::Cpu::Type type) const;