diff --git a/src/jit_compiler_a64.cpp b/src/jit_compiler_a64.cpp
index bfca39b4..d2a1d6c3 100644
--- a/src/jit_compiler_a64.cpp
+++ b/src/jit_compiler_a64.cpp
@@ -639,7 +639,16 @@ void JitCompilerA64::h_ISUB_R(Instruction& instr, uint32_t& codePos)
 	}
 	else
 	{
-		emitAddImmediate(dst, dst, -instr.getImm32(), code, k);
+		const uint32_t imm = instr.getImm32();
+
+		if (imm == 0x80000000ul) {
+			constexpr uint32_t tmp_reg = 20;
+			emit32(ARMV8A::MOVZ | tmp_reg | (1u << 21) | (0x8000u << 5), code, k);
+			emit32(ARMV8A::ADD | dst | (dst << 5) | (tmp_reg << 16), code, k);
+		}
+		else {
+			emitAddImmediate(dst, dst, -instr.getImm32(), code, k);
+		}
 	}
 
 	reg_changed_offset[instr.dst] = k;
diff --git a/src/jit_compiler_rv64.cpp b/src/jit_compiler_rv64.cpp
index 13552726..344a82f5 100644
--- a/src/jit_compiler_rv64.cpp
+++ b/src/jit_compiler_rv64.cpp
@@ -789,9 +789,16 @@ namespace randomx {
 			state.emit(rvi(rv64::SUB, regR(isn.dst), regR(isn.dst), regR(isn.src)));
 		}
 		else {
-			int32_t imm = unsigned32ToSigned2sCompl(-isn.getImm32()); //convert to add
-			//x{dst} = x{dst} + {-imm}
-			emitImm32(state, imm, regR(isn.dst), regR(isn.dst), Tmp1Reg);
+			const uint32_t uimm = isn.getImm32();
+			if (uimm == 0x80000000ul) {
+				state.emit(rv64::LUI | (0x80000 << 12) | rvrd(Tmp1Reg));
+				state.emit(rvi(rv64::SUB, regR(isn.dst), regR(isn.dst), Tmp1Reg));
+			}
+			else {
+				int32_t imm = unsigned32ToSigned2sCompl(-uimm); //convert to add
+				//x{dst} = x{dst} + {-imm}
+				emitImm32(state, imm, regR(isn.dst), regR(isn.dst), Tmp1Reg);
+			}
 		}
 	}
 
diff --git a/src/jit_compiler_rv64_vector.cpp b/src/jit_compiler_rv64_vector.cpp
index 772f8db6..01c959eb 100644
--- a/src/jit_compiler_rv64_vector.cpp
+++ b/src/jit_compiler_rv64_vector.cpp
@@ -448,6 +448,12 @@ void* generateProgramVectorRV64(uint8_t* buf, Program& prog, ProgramConfiguratio
 				// sub x20 + dst, x20 + dst, x20 + src
 				emit32(0x414A0A33 + (dst << 7) + (dst << 15) + (src << 20));
 			}
+			else if (imm == 0x80000000U) {
+				// lui x5, 0x80000000U
+				emit32(0x800002B7);
+				// sub x20 + dst, x20 + dst, x5
+				emit32(0x405A0A33 + (dst << 7) + (dst << 15));
+			}
 			else {
 				imm_to_x5(-imm, p);
 				// c.add x20 + dst, x5
diff --git a/src/tests/tests.cpp b/src/tests/tests.cpp
index f4cbd1c7..109dcd99 100644
--- a/src/tests/tests.cpp
+++ b/src/tests/tests.cpp
@@ -60,7 +60,7 @@ void runTest(const char* name, bool condition, FUNC f) {
 	std::cout << "[";
 	std::cout.width(2);
 	std::cout << std::right << ++testNo << "] ";
-	std::cout.width(40);
+	std::cout.width(44);
 	std::cout << std::left << name << " ... ";
 	std::cout.flush();
 	if (condition) {
@@ -1002,11 +1002,26 @@ int main() {
 		assert(equalsHex(hash, (vm->getFlags() & RANDOMX_FLAG_V2) ? "c8e92c5f7c1946fecf06bc382b92e3111da38ee3e6a5ad90704e1a9d8aaf6e76" : "c56414121acda1713c2f2a819d8ae38aed7c80c35c2a769298d34f03833cd5f1"));
 	};
 
+	auto test_f = [&] {
+		uint8_t key_u[RANDOMX_HASH_SIZE] = {
+			0x77, 0x97, 0x37, 0x3e, 0xa4, 0x63, 0x31, 0x94, 0x64, 0x0b, 0xf8, 0xd8, 0xc3, 0xb6, 0x67, 0x24, 0xd6, 0xaa, 0x7b, 0xd2, 0xdc, 0x20, 0xe0, 0x09, 0xdf, 0x2f, 0x8f, 0x17, 0x10, 0xab, 0xe8, 0x24
+		};
+		char key[RANDOMX_HASH_SIZE];
+
+		// workaround for picky compilers
+		memcpy(key, key_u, sizeof(key_u));
+
+		char hash[RANDOMX_HASH_SIZE];
+		calcHexHash(key, "1010e1eaf8cf067b37b5f0ee031ab23ed1755e090a3af4415830145853e2be3e1f6821fed84dae58d00e00da5214d6c1f2d0622e0abd51f9373d04e0b0f8e6d6514d90689721c4aac5a9bb0d", &hash);
+		assert(equalsHex(hash, "78af2a1864c42abce36d2e8983e13df99b2af0ce1362999af09fab004d4435a8"));
+	};
+
 	runTest("Hash test 1a (interpreter)", stringsEqual(RANDOMX_ARGON_SALT, "RandomX\x03"), test_a);
 	runTest("Hash test 1b (interpreter)", stringsEqual(RANDOMX_ARGON_SALT, "RandomX\x03"), test_b);
 	runTest("Hash test 1c (interpreter)", stringsEqual(RANDOMX_ARGON_SALT, "RandomX\x03"), test_c);
 	runTest("Hash test 1d (interpreter)", stringsEqual(RANDOMX_ARGON_SALT, "RandomX\x03"), test_d);
 	runTest("Hash test 1e (interpreter)", stringsEqual(RANDOMX_ARGON_SALT, "RandomX\x03"), test_e);
+	runTest("Hash test 1f (ISUB_R edge case, interpreter)", stringsEqual(RANDOMX_ARGON_SALT, "RandomX\x03"), test_f);
 
 	randomx_destroy_vm(vm);
 
@@ -1040,6 +1055,7 @@ int main() {
 	runTest("Hash test 2c (compiler)", RANDOMX_HAVE_COMPILER && stringsEqual(RANDOMX_ARGON_SALT, "RandomX\x03"), test_c);
 	runTest("Hash test 2d (compiler)", RANDOMX_HAVE_COMPILER && stringsEqual(RANDOMX_ARGON_SALT, "RandomX\x03"), test_d);
 	runTest("Hash test 2e (compiler)", RANDOMX_HAVE_COMPILER && stringsEqual(RANDOMX_ARGON_SALT, "RandomX\x03"), test_e);
+	runTest("Hash test 2f (ISUB_R edge case, compiler)", RANDOMX_HAVE_COMPILER && stringsEqual(RANDOMX_ARGON_SALT, "RandomX\x03"), test_f);
 
 	if (RANDOMX_HAVE_COMPILER) {
 		randomx_destroy_vm(vm);