diff --git a/mlir/lib/Dialect/SparseTensor/Transforms/Sparsification.cpp b/mlir/lib/Dialect/SparseTensor/Transforms/Sparsification.cpp
--- a/mlir/lib/Dialect/SparseTensor/Transforms/Sparsification.cpp
+++ b/mlir/lib/Dialect/SparseTensor/Transforms/Sparsification.cpp
@@ -1854,13 +1854,13 @@
                                 PatternRewriter &rewriter) const override {
     // Detects sparse annotations and translate the per-dimension sparsity
     // information for all tensors to loop indices in the kernel.
-    assert(op.getNumOutputs() == 1);
     unsigned numTensors = op.getNumInputsAndOutputs();
     unsigned numLoops = op.iterator_types().getValue().size();
     Merger merger(numTensors, numLoops);
     if (!findSparseAnnotations(merger, op))
       return failure();
 
+    assert(op.getNumOutputs() == 1);
     // Builds the tensor expression for the Linalg operation in SSA form.
     Optional<unsigned> optExp = merger.buildTensorExpFromLinalg(op);
     if (!optExp.has_value())