diff --git a/rvfi/insns/insn_mulh.py b/rvfi/insns/insn_mulh.py
index 0998752..8175f58 100644
--- a/rvfi/insns/insn_mulh.py
+++ b/rvfi/insns/insn_mulh.py
@@ -1,5 +1,9 @@
 from .insn_rv32m_r_type import *
 
+"""
+MULH instruction
+"""
+
 class InsnMulh(InsnRV32MRType):
     def __init__(self, params):
         super().__init__(params, 0b001)
diff --git a/rvfi/insns/insn_mulhsu.py b/rvfi/insns/insn_mulhsu.py
new file mode 100644
index 0000000..a5ffca7
--- /dev/null
+++ b/rvfi/insns/insn_mulhsu.py
@@ -0,0 +1,18 @@
+from .insn_rv32m_r_type import *
+
+"""
+MULHSU instruction
+"""
+
+class InsnMulhsu(InsnRV32MRType):
+    def __init__(self, params):
+        super().__init__(params, 0b010)
+    def elaborate(self, platform):
+        m = super().elaborate(platform)
+
+        if self.params.altops:
+            m.d.comb += self.spec_rd_wdata.eq(Mux(self.spec_rd_addr, (self.rvfi_rs1_rdata - self.rvfi_rs2_rdata) ^ 0xea3969edecfbe137, 0))
+        else:
+            m.d.comb += self.spec_rd_wdata.eq(Mux(self.spec_rd_addr, (((Mux(self.rvfi_rs1_rdata[-1], 2 ** self.params.xlen - 1, 0) << self.params.xlen) | self.rvfi_rs1_rdata) * self.rvfi_rs2_rdata) >> self.params.xlen, 0))
+
+        return m