diff --git a/mlir/lib/Dialect/Vector/Transforms/VectorTransforms.cpp b/mlir/lib/Dialect/Vector/Transforms/VectorTransforms.cpp
--- a/mlir/lib/Dialect/Vector/Transforms/VectorTransforms.cpp
+++ b/mlir/lib/Dialect/Vector/Transforms/VectorTransforms.cpp
@@ -2503,6 +2503,13 @@
     if (rank != insertOp.getDestVectorType().getRank())
       return failure();
 
+    // Requires that shape of insert op src is castable to dstType.
+    unsigned srcWidth = castSrcType.getElementType().getIntOrFloatBitWidth();
+    unsigned dstWidth = castDstType.getElementType().getIntOrFloatBitWidth();
+    unsigned unitCastNumel = dstWidth / srcWidth;
+    if (insertOp.getSourceVectorType().getNumElements() % unitCastNumel != 0)
+      return failure();
+
     ArrayAttr newOffsets = insertOp.getOffsets();
     assert(newOffsets.size() == rank);
     SmallVector<int64_t, 4> offsets = getIntValueVector(newOffsets);