diff --git a/lib/Target/ARM/Disassembler/ARMDisassemblerCore.cpp b/lib/Target/ARM/Disassembler/ARMDisassemblerCore.cpp
index 5eda8e14bbd..0301643970b 100644
--- a/lib/Target/ARM/Disassembler/ARMDisassemblerCore.cpp
+++ b/lib/Target/ARM/Disassembler/ARMDisassemblerCore.cpp
@@ -2104,7 +2104,7 @@ static uint64_t decodeN1VImm(uint32_t insn, ElemSize esize) {
   case ESize64: {
     for (unsigned i = 0; i < 8; ++i)
       if ((Imm8 >> i) & 1)
-        Imm64 |= 0xFFul << 8*i;
+        Imm64 |= (uint64_t)0xFF << 8*i;
     break;
   }
   default: