diff --git a/llvm/lib/Target/RISCV/Disassembler/RISCVDisassembler.cpp b/llvm/lib/Target/RISCV/Disassembler/RISCVDisassembler.cpp
index 27e04c0cb1f8b..52061e96d0018 100644
--- a/llvm/lib/Target/RISCV/Disassembler/RISCVDisassembler.cpp
+++ b/llvm/lib/Target/RISCV/Disassembler/RISCVDisassembler.cpp
@@ -811,7 +811,9 @@ DecodeStatus RISCVDisassembler::getInstruction32(MCInst &MI, uint64_t &Size,
   }
   Size = 4;
 
-  uint32_t Insn = support::endian::read32le(Bytes.data());
+  // Use uint64_t to match getInstruction48. decodeInstruction is templated
+  // on the Insn type.
+  uint64_t Insn = support::endian::read32le(Bytes.data());
 
   for (const DecoderListEntry &Entry : DecoderList32) {
     if (!Entry.haveContainedFeatures(STI.getFeatureBits()))
@@ -857,7 +859,9 @@ DecodeStatus RISCVDisassembler::getInstruction16(MCInst &MI, uint64_t &Size,
   }
   Size = 2;
 
-  uint32_t Insn = support::endian::read16le(Bytes.data());
+  // Use uint64_t to match getInstruction48. decodeInstruction is templated
+  // on the Insn type.
+  uint64_t Insn = support::endian::read16le(Bytes.data());
 
   for (const DecoderListEntry &Entry : DecoderList16) {
     if (!Entry.haveContainedFeatures(STI.getFeatureBits()))