diff --git a/mlir/lib/Dialect/Linalg/IR/LinalgInterfaces.cpp b/mlir/lib/Dialect/Linalg/IR/LinalgInterfaces.cpp
--- a/mlir/lib/Dialect/Linalg/IR/LinalgInterfaces.cpp
+++ b/mlir/lib/Dialect/Linalg/IR/LinalgInterfaces.cpp
@@ -573,6 +573,15 @@
            << ") to be equal to the number of output tensors ("
            << linalgOp.getOutputTensorOperands().size() << ")";
 
+  // Check all iterator types are known.
+  auto iteratorTypesRange =
+      linalgOp.iterator_types().getAsValueRange<StringAttr>();
+  for (StringRef iteratorType : iteratorTypesRange) {
+    if (!llvm::is_contained(getAllIteratorTypeNames(), iteratorType))
+      return op->emitOpError("unexpected iterator_type (")
+             << iteratorType << ")";
+  }
+
   // Before checking indexing maps, we need to make sure the attributes
   // referenced by it are valid.
   if (linalgOp.hasDynamicIndexingMaps())
diff --git a/mlir/test/Dialect/Linalg/invalid.mlir b/mlir/test/Dialect/Linalg/invalid.mlir
--- a/mlir/test/Dialect/Linalg/invalid.mlir
+++ b/mlir/test/Dialect/Linalg/invalid.mlir
@@ -95,6 +95,19 @@
 
 // -----
 
+func @generic_wrong_iterator(%arg0: memref<1xi32>) {
+  // expected-error @+1 {{op unexpected iterator_type (random)}}
+  linalg.generic {
+    indexing_maps =  [ affine_map<(i) -> (i)> ],
+    iterator_types = ["random"]}
+      outs(%arg0 : memref<1xi32>) {
+    ^bb(%i : i32):
+    linalg.yield %i : i32
+  }
+}
+
+// -----
+
 func @generic_one_d_view(%arg0: memref<?xf32, affine_map<(i)[off]->(off + i)>>) {
   // expected-error @+1 {{expected operand rank (1) to match the result rank of indexing_map #0 (2)}}
   linalg.generic {