diff --git a/riscv/mmu.h b/riscv/mmu.h
index d5f59a07..7bc5fe7d 100644
--- a/riscv/mmu.h
+++ b/riscv/mmu.h
@@ -315,7 +315,7 @@ public:
     unsigned length = insn_length(insn);
 
     for (unsigned pos = sizeof(insn_parcel_t); pos < length; pos += sizeof(insn_parcel_t)) {
-      insn |= fetch_insn_parcel(addr + pos) << (8 * pos);
+      insn |= (insn_bits_t)fetch_insn_parcel(addr + pos) << (8 * pos);
       length = insn_length(insn);
     }