diff --git a/src/disassembler_mips.cc b/src/disassembler_mips.cc
index a281796..7fba4a8 100644
--- a/src/disassembler_mips.cc
+++ b/src/disassembler_mips.cc
@@ -128,16 +128,16 @@
   { kITypeMask, 14 << kOpcodeShift, "ori", "TSi", },
   { kITypeMask, 15 << kOpcodeShift, "lui", "TI", },
 
-  { kITypeMask, 32 << kOpcodeShift, "lb", "TO", },
-  { kITypeMask, 33 << kOpcodeShift, "lh", "TO", },
-  { kITypeMask, 35 << kOpcodeShift, "lw", "TO", },
-  { kITypeMask, 36 << kOpcodeShift, "lbu", "TO", },
-  { kITypeMask, 37 << kOpcodeShift, "lhu", "TO", },
-  { kITypeMask, 40 << kOpcodeShift, "sb", "TO", },
-  { kITypeMask, 41 << kOpcodeShift, "sh", "TO", },
-  { kITypeMask, 43 << kOpcodeShift, "sw", "TO", },
-  { kITypeMask, 49 << kOpcodeShift, "lwc1", "tO", },
-  { kITypeMask, 57 << kOpcodeShift, "swc1", "tO", },
+  { kITypeMask, 32u << kOpcodeShift, "lb", "TO", },
+  { kITypeMask, 33u << kOpcodeShift, "lh", "TO", },
+  { kITypeMask, 35u << kOpcodeShift, "lw", "TO", },
+  { kITypeMask, 36u << kOpcodeShift, "lbu", "TO", },
+  { kITypeMask, 37u << kOpcodeShift, "lhu", "TO", },
+  { kITypeMask, 40u << kOpcodeShift, "sb", "TO", },
+  { kITypeMask, 41u << kOpcodeShift, "sh", "TO", },
+  { kITypeMask, 43u << kOpcodeShift, "sw", "TO", },
+  { kITypeMask, 49u << kOpcodeShift, "lwc1", "tO", },
+  { kITypeMask, 57u << kOpcodeShift, "swc1", "tO", },
 
   // Floating point.
   { kFpMask,                kCop1 | 0, "add", "fdst" },