diff --git a/src/reader/wgsl/parser_impl.cc b/src/reader/wgsl/parser_impl.cc
index 9aaea82..493ac84 100644
--- a/src/reader/wgsl/parser_impl.cc
+++ b/src/reader/wgsl/parser_impl.cc
@@ -1110,14 +1110,14 @@
   uint32_t rows = 2;
   uint32_t columns = 2;
   if (t.IsMat3x2() || t.IsMat3x3() || t.IsMat3x4()) {
-    rows = 3;
+    columns = 3;
   } else if (t.IsMat4x2() || t.IsMat4x3() || t.IsMat4x4()) {
-    rows = 4;
+    columns = 4;
   }
   if (t.IsMat2x3() || t.IsMat3x3() || t.IsMat4x3()) {
-    columns = 3;
+    rows = 3;
   } else if (t.IsMat2x4() || t.IsMat3x4() || t.IsMat4x4()) {
-    columns = 4;
+    rows = 4;
   }
 
   const char* use = "matrix";
diff --git a/src/reader/wgsl/parser_impl_type_decl_test.cc b/src/reader/wgsl/parser_impl_type_decl_test.cc
index 6c11ba1..9251526 100644
--- a/src/reader/wgsl/parser_impl_type_decl_test.cc
+++ b/src/reader/wgsl/parser_impl_type_decl_test.cc
@@ -604,8 +604,8 @@
 
 struct MatrixData {
   const char* input;
-  size_t rows;
   size_t columns;
+  size_t rows;
 };
 inline std::ostream& operator<<(std::ostream& out, MatrixData data) {
   out << std::string(data.input);