diff --git a/src/transform/first_index_offset.cc b/src/transform/first_index_offset.cc
index 29fe53f8c3..f5f3026fce 100644
--- a/src/transform/first_index_offset.cc
+++ b/src/transform/first_index_offset.cc
@@ -86,11 +86,11 @@ ast::Variable* clone_variable_with_new_name(CloneContext* ctx,
 FirstIndexOffset::Data::Data(bool has_vtx_index,
                              bool has_inst_index,
                              uint32_t first_vtx_offset,
-                             uint32_t first_idx_offset)
+                             uint32_t first_inst_offset)
     : has_vertex_index(has_vtx_index),
       has_instance_index(has_inst_index),
       first_vertex_offset(first_vtx_offset),
-      first_index_offset(first_idx_offset) {}
+      first_instance_offset(first_inst_offset) {}
 
 FirstIndexOffset::Data::Data(const Data&) = default;
 
diff --git a/src/transform/first_index_offset.h b/src/transform/first_index_offset.h
index dfb0353f58..ab642c4e99 100644
--- a/src/transform/first_index_offset.h
+++ b/src/transform/first_index_offset.h
@@ -68,11 +68,11 @@ class FirstIndexOffset : public Transform {
     /// @param has_vtx_index True if the shader uses vertex_index
     /// @param has_inst_index True if the shader uses instance_index
     /// @param first_vtx_offset Offset of first vertex into constant buffer
-    /// @param first_idx_offset Offset of first instance into constant buffer
+    /// @param first_inst_offset Offset of first instance into constant buffer
     Data(bool has_vtx_index,
          bool has_inst_index,
          uint32_t first_vtx_offset,
-         uint32_t first_idx_offset);
+         uint32_t first_inst_offset);
 
     /// Copy constructor
     Data(const Data&);
@@ -87,7 +87,7 @@ class FirstIndexOffset : public Transform {
     /// Offset of first vertex into constant buffer
     uint32_t const first_vertex_offset;
     /// Offset of first instance into constant buffer
-    uint32_t const first_index_offset;
+    uint32_t const first_instance_offset;
   };
 
   /// Constructor
diff --git a/src/transform/first_index_offset_test.cc b/src/transform/first_index_offset_test.cc
index c102c9d556..46189157e8 100644
--- a/src/transform/first_index_offset_test.cc
+++ b/src/transform/first_index_offset_test.cc
@@ -57,7 +57,7 @@ fn entry() -> void {
   EXPECT_EQ(data->has_vertex_index, true);
   EXPECT_EQ(data->has_instance_index, false);
   EXPECT_EQ(data->first_vertex_offset, 0u);
-  EXPECT_EQ(data->first_index_offset, 0u);
+  EXPECT_EQ(data->first_instance_offset, 0u);
 }
 
 TEST_F(FirstIndexOffsetTest, EmptyModule) {
@@ -74,7 +74,7 @@ TEST_F(FirstIndexOffsetTest, EmptyModule) {
   EXPECT_EQ(data->has_vertex_index, false);
   EXPECT_EQ(data->has_instance_index, false);
   EXPECT_EQ(data->first_vertex_offset, 0u);
-  EXPECT_EQ(data->first_index_offset, 0u);
+  EXPECT_EQ(data->first_instance_offset, 0u);
 }
 
 TEST_F(FirstIndexOffsetTest, BasicModuleVertexIndex) {
@@ -123,7 +123,7 @@ fn entry() -> void {
   EXPECT_EQ(data->has_vertex_index, true);
   EXPECT_EQ(data->has_instance_index, false);
   EXPECT_EQ(data->first_vertex_offset, 0u);
-  EXPECT_EQ(data->first_index_offset, 0u);
+  EXPECT_EQ(data->first_instance_offset, 0u);
 }
 
 TEST_F(FirstIndexOffsetTest, BasicModuleInstanceIndex) {
@@ -172,7 +172,7 @@ fn entry() -> void {
   EXPECT_EQ(data->has_vertex_index, false);
   EXPECT_EQ(data->has_instance_index, true);
   EXPECT_EQ(data->first_vertex_offset, 0u);
-  EXPECT_EQ(data->first_index_offset, 0u);
+  EXPECT_EQ(data->first_instance_offset, 0u);
 }
 
 TEST_F(FirstIndexOffsetTest, BasicModuleBothIndex) {
@@ -227,7 +227,7 @@ fn entry() -> void {
   EXPECT_EQ(data->has_vertex_index, true);
   EXPECT_EQ(data->has_instance_index, true);
   EXPECT_EQ(data->first_vertex_offset, 0u);
-  EXPECT_EQ(data->first_index_offset, 4u);
+  EXPECT_EQ(data->first_instance_offset, 4u);
 }
 
 TEST_F(FirstIndexOffsetTest, NestedCalls) {
@@ -284,7 +284,7 @@ fn entry() -> void {
   EXPECT_EQ(data->has_vertex_index, true);
   EXPECT_EQ(data->has_instance_index, false);
   EXPECT_EQ(data->first_vertex_offset, 0u);
-  EXPECT_EQ(data->first_index_offset, 0u);
+  EXPECT_EQ(data->first_instance_offset, 0u);
 }
 
 }  // namespace