diff --git a/clang/lib/Sema/SemaRISCVVectorLookup.cpp b/clang/lib/Sema/SemaRISCVVectorLookup.cpp
index f2cfa7db5c8df..981ab5f13716d 100644
--- a/clang/lib/Sema/SemaRISCVVectorLookup.cpp
+++ b/clang/lib/Sema/SemaRISCVVectorLookup.cpp
@@ -87,6 +87,7 @@ ProtoSeq2ArrayRef(IntrinsicKind K, uint16_t Index, uint8_t Length) {
   case IntrinsicKind::SIFIVE_VECTOR:
     return ArrayRef(&RVSiFiveVectorSignatureTable[Index], Length);
   }
+  llvm_unreachable("Unhandled IntrinsicKind");
 }
 
 static QualType RVVType2Qual(ASTContext &Context, const RVVType *Type) {