diff --git a/src/tint/reader/wgsl/parser_impl.cc b/src/tint/reader/wgsl/parser_impl.cc
index 1d8182189d..e4eab291af 100644
--- a/src/tint/reader/wgsl/parser_impl.cc
+++ b/src/tint/reader/wgsl/parser_impl.cc
@@ -214,7 +214,7 @@ ParserImpl::~ParserImpl() = default;
 ParserImpl::Failure::Errored ParserImpl::add_error(const Source& source,
                                                    std::string_view err,
                                                    std::string_view use) {
-    std::stringstream msg;
+    utils::StringStream msg;
     msg << err;
     if (!use.empty()) {
         msg << " for " << use;
@@ -3165,7 +3165,7 @@ bool ParserImpl::expect(std::string_view use, Token::Type tok) {
         return false;
     }
 
-    std::stringstream err;
+    utils::StringStream err;
     if (tok == Token::Type::kTemplateArgsLeft && t.type() == Token::Type::kLessThan) {
         err << "missing closing '>'";
     } else {
diff --git a/src/tint/reader/wgsl/parser_impl_error_msg_test.cc b/src/tint/reader/wgsl/parser_impl_error_msg_test.cc
index 85e55cb518..af5089492e 100644
--- a/src/tint/reader/wgsl/parser_impl_error_msg_test.cc
+++ b/src/tint/reader/wgsl/parser_impl_error_msg_test.cc
@@ -14,6 +14,8 @@
 
 #include "src/tint/reader/wgsl/parser_impl_test_helper.h"
 
+#include "src/tint/utils/string_stream.h"
+
 namespace tint::reader::wgsl {
 namespace {
 
@@ -513,8 +515,8 @@ const i : vec2<i32> = vec2<i32>(!);
 TEST_F(ParserImplErrorTest, GlobalDeclConstExprMaxDepth) {
     uint32_t kMaxDepth = 128;
 
-    std::stringstream src;
-    std::stringstream mkr;
+    utils::StringStream src;
+    utils::StringStream mkr;
     src << "const i : i32 = ";
     mkr << "                ";
     for (size_t i = 0; i < kMaxDepth + 8; i++) {
@@ -530,7 +532,7 @@ TEST_F(ParserImplErrorTest, GlobalDeclConstExprMaxDepth) {
         src << ")";
     }
     src << ";";
-    std::stringstream err;
+    utils::StringStream err;
     err << "test.wgsl:1:529 error: maximum parser recursive depth reached\n"
         << src.str() << "\n"
         << mkr.str() << "\n";
diff --git a/src/tint/reader/wgsl/parser_impl_expression_test.cc b/src/tint/reader/wgsl/parser_impl_expression_test.cc
index 0de3dea890..9a6c9179b3 100644
--- a/src/tint/reader/wgsl/parser_impl_expression_test.cc
+++ b/src/tint/reader/wgsl/parser_impl_expression_test.cc
@@ -14,6 +14,8 @@
 
 #include "src/tint/reader/wgsl/parser_impl_test_helper.h"
 
+#include "src/tint/utils/string_stream.h"
+
 namespace tint::reader::wgsl {
 namespace {
 
@@ -486,7 +488,7 @@ static std::vector<Case> Cases() {
 using ParserImplMixedBinaryOpTest = ParserImplTestWithParam<Case>;
 
 TEST_P(ParserImplMixedBinaryOpTest, Test) {
-    std::stringstream wgsl;
+    utils::StringStream wgsl;
     wgsl << GetParam();
     auto p = parser(wgsl.str());
     auto e = p->expression();
@@ -498,7 +500,7 @@ TEST_P(ParserImplMixedBinaryOpTest, Test) {
         EXPECT_TRUE(e.errored);
         EXPECT_EQ(e.value, nullptr);
         EXPECT_TRUE(p->has_error());
-        std::stringstream expected;
+        utils::StringStream expected;
         expected << "1:3: mixing '" << GetParam().lhs_op.symbol << "' and '"
                  << GetParam().rhs_op.symbol << "' requires parenthesis";
         EXPECT_EQ(p->error(), expected.str());