diff --git a/src/program.cc b/src/program.cc
index f341e8acf2..3fbf4c9126 100644
--- a/src/program.cc
+++ b/src/program.cc
@@ -40,7 +40,7 @@ Program::Program(Program&& program)
 Program::Program(ProgramBuilder&& builder) {
   is_valid_ = builder.IsValid();
   if (builder.ResolveOnBuild() && builder.IsValid()) {
-    Resolver resolver(&builder);
+    resolver::Resolver resolver(&builder);
     if (!resolver.Resolve()) {
       diagnostics_.add_error(resolver.error());
       is_valid_ = false;
diff --git a/src/resolver/resolver.cc b/src/resolver/resolver.cc
index da144c7b30..07a3c93a91 100644
--- a/src/resolver/resolver.cc
+++ b/src/resolver/resolver.cc
@@ -37,6 +37,7 @@
 #include "src/semantic/variable.h"
 
 namespace tint {
+namespace resolver {
 namespace {
 
 using IntrinsicType = tint::semantic::IntrinsicType;
@@ -961,4 +962,5 @@ Resolver::FunctionInfo::FunctionInfo(ast::Function* decl) : declaration(decl) {}
 
 Resolver::FunctionInfo::~FunctionInfo() = default;
 
+}  // namespace resolver
 }  // namespace tint
diff --git a/src/resolver/resolver.h b/src/resolver/resolver.h
index 4a095be7b8..53b38e83e2 100644
--- a/src/resolver/resolver.h
+++ b/src/resolver/resolver.h
@@ -45,6 +45,8 @@ namespace semantic {
 class Statement;
 }  // namespace semantic
 
+namespace resolver {
+
 /// Resolves types for all items in the given tint program
 class Resolver {
  public:
@@ -241,6 +243,7 @@ class Resolver {
   BlockAllocator<FunctionInfo> function_infos_;
 };
 
+}  // namespace resolver
 }  // namespace tint
 
 #endif  // SRC_RESOLVER_RESOLVER_H_
diff --git a/src/resolver/resolver_test.cc b/src/resolver/resolver_test.cc
index d3613cd147..3f899a2125 100644
--- a/src/resolver/resolver_test.cc
+++ b/src/resolver/resolver_test.cc
@@ -40,6 +40,7 @@ using ::testing::ElementsAre;
 using ::testing::HasSubstr;
 
 namespace tint {
+namespace resolver {
 namespace {
 
 using IntrinsicType = semantic::IntrinsicType;
@@ -3774,10 +3775,11 @@ TEST_P(ResolverTextureIntrinsicTest, Call) {
   auto* target = call_sem->Target();
   ASSERT_NE(target, nullptr);
 
-  auto got = ::tint::to_str(param.function, target->Parameters());
+  auto got = resolver::to_str(param.function, target->Parameters());
   auto* expected = expected_texture_overload(param.overload);
   EXPECT_EQ(got, expected);
 }
 
 }  // namespace
+}  // namespace resolver
 }  // namespace tint