diff --git a/mlir/lib/Dialect/SparseTensor/Transforms/SparseTensorCodegen.cpp b/mlir/lib/Dialect/SparseTensor/Transforms/SparseTensorCodegen.cpp
--- a/mlir/lib/Dialect/SparseTensor/Transforms/SparseTensorCodegen.cpp
+++ b/mlir/lib/Dialect/SparseTensor/Transforms/SparseTensorCodegen.cpp
@@ -745,6 +745,17 @@
 mlir::SparseTensorTypeToBufferConverter::SparseTensorTypeToBufferConverter() {
   addConversion([](Type type) { return type; });
   addConversion(convertSparseTensorType);
+
+  // Required by scf.for 1:N type conversion.
+  addSourceMaterialization([](OpBuilder &builder, RankedTensorType tp,
+                              ValueRange inputs,
+                              Location loc) -> Optional<Value> {
+    if (!getSparseTensorEncoding(tp))
+      // Not a sparse tensor.
+      return llvm::None;
+    // Sparse compiler knows how to cancel out these casts.
+    return genTuple(builder, loc, tp, inputs);
+  });
 }
 
 //===----------------------------------------------------------------------===//