diff --git a/mlir/lib/Dialect/SparseTensor/Utils/Merger.cpp b/mlir/lib/Dialect/SparseTensor/Utils/Merger.cpp
index 1d81dafcd0eb8..78771d1a90835 100644
--- a/mlir/lib/Dialect/SparseTensor/Utils/Merger.cpp
+++ b/mlir/lib/Dialect/SparseTensor/Utils/Merger.cpp
@@ -377,6 +377,7 @@ bool Merger::isSingleCondition(unsigned t, unsigned e) const {
   case kBinary:
     return false;
   }
+  llvm_unreachable("unexpected kind");
 }
 
 #ifndef NDEBUG