diff --git a/DevTools/UserspaceEmulator/SoftCPU.cpp b/DevTools/UserspaceEmulator/SoftCPU.cpp
index 44581cc517..57f4677bd9 100644
--- a/DevTools/UserspaceEmulator/SoftCPU.cpp
+++ b/DevTools/UserspaceEmulator/SoftCPU.cpp
@@ -1055,9 +1055,20 @@ void SoftCPU::MOVSW(const X86::Instruction& insn)
         });
     }
 }
-void SoftCPU::MOVSX_reg16_RM8(const X86::Instruction&) { TODO(); }
-void SoftCPU::MOVSX_reg32_RM16(const X86::Instruction&) { TODO(); }
-void SoftCPU::MOVSX_reg32_RM8(const X86::Instruction&) { TODO(); }
+void SoftCPU::MOVSX_reg16_RM8(const X86::Instruction& insn)
+{
+    gpr16(insn.reg16()) = sign_extended_to<u16>(insn.modrm().read8(*this, insn));
+}
+
+void SoftCPU::MOVSX_reg32_RM16(const X86::Instruction& insn)
+{
+    gpr32(insn.reg32()) = sign_extended_to<u32>(insn.modrm().read16(*this, insn));
+}
+
+void SoftCPU::MOVSX_reg32_RM8(const X86::Instruction& insn)
+{
+    gpr32(insn.reg32()) = sign_extended_to<u32>(insn.modrm().read8(*this, insn));
+}
 
 void SoftCPU::MOVZX_reg16_RM8(const X86::Instruction& insn)
 {