diff --git a/src/arch/x86/isa/microops/mediaop.isa b/src/arch/x86/isa/microops/mediaop.isa
index 0d6c7a395..35e0f8f35 100644
--- a/src/arch/x86/isa/microops/mediaop.isa
+++ b/src/arch/x86/isa/microops/mediaop.isa
@@ -355,4 +355,11 @@ let {{
         code = '''
             FpDestReg.uqw = FpSrcReg1.uqw & FpSrcReg2.uqw;
         '''
+
+    class Mandn(MediaOp):
+        def __init__(self, dest, src1, src2):
+            super(Mandn, self).__init__(dest, src1, src2, 1)
+        code = '''
+            FpDestReg.uqw = ~FpSrcReg1.uqw & FpSrcReg2.uqw;
+        '''
 }};