diff --git a/include/valijson/adapters/boost_json_adapter.hpp b/include/valijson/adapters/boost_json_adapter.hpp
index f2f4ea4..2b83fd1 100644
--- a/include/valijson/adapters/boost_json_adapter.hpp
+++ b/include/valijson/adapters/boost_json_adapter.hpp
@@ -29,9 +29,9 @@
 
 #include <boost/json.hpp>
 
-#include <valijson/adapters/adapter.hpp>
-#include <valijson/adapters/basic_adapter.hpp>
-#include <valijson/adapters/frozen_value.hpp>
+#include <valijson/internal/adapter.hpp>
+#include <valijson/internal/basic_adapter.hpp>
+#include <valijson/internal/frozen_value.hpp>
 
 namespace valijson {
 namespace adapters {
diff --git a/include/valijson/adapters/json11_adapter.hpp b/include/valijson/adapters/json11_adapter.hpp
index 41749b2..6cab445 100644
--- a/include/valijson/adapters/json11_adapter.hpp
+++ b/include/valijson/adapters/json11_adapter.hpp
@@ -28,9 +28,9 @@
 #include <string>
 #include <json11.hpp>
 
-#include <valijson/adapters/adapter.hpp>
-#include <valijson/adapters/basic_adapter.hpp>
-#include <valijson/adapters/frozen_value.hpp>
+#include <valijson/internal/adapter.hpp>
+#include <valijson/internal/basic_adapter.hpp>
+#include <valijson/internal/frozen_value.hpp>
 #include <valijson/exceptions.hpp>
 
 namespace valijson {
diff --git a/include/valijson/adapters/jsoncpp_adapter.hpp b/include/valijson/adapters/jsoncpp_adapter.hpp
index 2fd1fe7..51a986f 100644
--- a/include/valijson/adapters/jsoncpp_adapter.hpp
+++ b/include/valijson/adapters/jsoncpp_adapter.hpp
@@ -31,9 +31,9 @@
 
 #include <json/json.h>
 
-#include <valijson/adapters/adapter.hpp>
-#include <valijson/adapters/basic_adapter.hpp>
-#include <valijson/adapters/frozen_value.hpp>
+#include <valijson/internal/adapter.hpp>
+#include <valijson/internal/basic_adapter.hpp>
+#include <valijson/internal/frozen_value.hpp>
 #include <valijson/exceptions.hpp>
 
 namespace valijson {
diff --git a/include/valijson/adapters/nlohmann_json_adapter.hpp b/include/valijson/adapters/nlohmann_json_adapter.hpp
index aeb1564..87c2705 100644
--- a/include/valijson/adapters/nlohmann_json_adapter.hpp
+++ b/include/valijson/adapters/nlohmann_json_adapter.hpp
@@ -28,9 +28,9 @@
 #include <string>
 #include <nlohmann/json.hpp>
 
-#include <valijson/adapters/adapter.hpp>
-#include <valijson/adapters/basic_adapter.hpp>
-#include <valijson/adapters/frozen_value.hpp>
+#include <valijson/internal/adapter.hpp>
+#include <valijson/internal/basic_adapter.hpp>
+#include <valijson/internal/frozen_value.hpp>
 #include <valijson/exceptions.hpp>
 #include <utility>
 
diff --git a/include/valijson/adapters/picojson_adapter.hpp b/include/valijson/adapters/picojson_adapter.hpp
index 4f5e5b6..ca3076f 100644
--- a/include/valijson/adapters/picojson_adapter.hpp
+++ b/include/valijson/adapters/picojson_adapter.hpp
@@ -35,9 +35,9 @@
 #include <picojson.h>
 #endif
 
-#include <valijson/adapters/adapter.hpp>
-#include <valijson/adapters/basic_adapter.hpp>
-#include <valijson/adapters/frozen_value.hpp>
+#include <valijson/internal/adapter.hpp>
+#include <valijson/internal/basic_adapter.hpp>
+#include <valijson/internal/frozen_value.hpp>
 #include <valijson/exceptions.hpp>
 
 namespace valijson {
diff --git a/include/valijson/adapters/poco_json_adapter.hpp b/include/valijson/adapters/poco_json_adapter.hpp
index 6bc5a3e..f9dfd28 100644
--- a/include/valijson/adapters/poco_json_adapter.hpp
+++ b/include/valijson/adapters/poco_json_adapter.hpp
@@ -28,9 +28,9 @@
 #include <string>
 #include <Poco/JSON/Object.h>
 
-#include <valijson/adapters/adapter.hpp>
-#include <valijson/adapters/basic_adapter.hpp>
-#include <valijson/adapters/frozen_value.hpp>
+#include <valijson/internal/adapter.hpp>
+#include <valijson/internal/basic_adapter.hpp>
+#include <valijson/internal/frozen_value.hpp>
 #include <valijson/exceptions.hpp>
 
 namespace valijson {
diff --git a/include/valijson/adapters/property_tree_adapter.hpp b/include/valijson/adapters/property_tree_adapter.hpp
index 425547f..83e2eb1 100644
--- a/include/valijson/adapters/property_tree_adapter.hpp
+++ b/include/valijson/adapters/property_tree_adapter.hpp
@@ -29,9 +29,9 @@
 
 #include <boost/property_tree/ptree.hpp>
 
-#include <valijson/adapters/adapter.hpp>
-#include <valijson/adapters/basic_adapter.hpp>
-#include <valijson/adapters/frozen_value.hpp>
+#include <valijson/internal/adapter.hpp>
+#include <valijson/internal/basic_adapter.hpp>
+#include <valijson/internal/frozen_value.hpp>
 
 namespace valijson {
 namespace adapters {
diff --git a/include/valijson/adapters/qtjson_adapter.hpp b/include/valijson/adapters/qtjson_adapter.hpp
index 2307fb5..023a075 100644
--- a/include/valijson/adapters/qtjson_adapter.hpp
+++ b/include/valijson/adapters/qtjson_adapter.hpp
@@ -32,9 +32,9 @@
 #include <QJsonValue>
 #include <QJsonArray>
 
-#include <valijson/adapters/adapter.hpp>
-#include <valijson/adapters/basic_adapter.hpp>
-#include <valijson/adapters/frozen_value.hpp>
+#include <valijson/internal/adapter.hpp>
+#include <valijson/internal/basic_adapter.hpp>
+#include <valijson/internal/frozen_value.hpp>
 #include <valijson/exceptions.hpp>
 
 namespace valijson {
diff --git a/include/valijson/adapters/rapidjson_adapter.hpp b/include/valijson/adapters/rapidjson_adapter.hpp
index c9ec75d..7df0b92 100644
--- a/include/valijson/adapters/rapidjson_adapter.hpp
+++ b/include/valijson/adapters/rapidjson_adapter.hpp
@@ -63,9 +63,9 @@
 
 #include <rapidjson/document.h>
 
-#include <valijson/adapters/adapter.hpp>
-#include <valijson/adapters/basic_adapter.hpp>
-#include <valijson/adapters/frozen_value.hpp>
+#include <valijson/internal/adapter.hpp>
+#include <valijson/internal/basic_adapter.hpp>
+#include <valijson/internal/frozen_value.hpp>
 #include <valijson/exceptions.hpp>
 
 namespace valijson {
diff --git a/include/valijson/adapters/std_string_adapter.hpp b/include/valijson/adapters/std_string_adapter.hpp
index 2084024..1da61b3 100644
--- a/include/valijson/adapters/std_string_adapter.hpp
+++ b/include/valijson/adapters/std_string_adapter.hpp
@@ -16,9 +16,9 @@
 
 #include <string>
 
-#include <valijson/adapters/adapter.hpp>
-#include <valijson/adapters/frozen_value.hpp>
-#include <valijson/adapters/basic_adapter.hpp>
+#include <valijson/internal/adapter.hpp>
+#include <valijson/internal/frozen_value.hpp>
+#include <valijson/internal/basic_adapter.hpp>
 #include <valijson/exceptions.hpp>
 
 namespace valijson {
diff --git a/include/valijson/adapters/yaml_cpp_adapter.hpp b/include/valijson/adapters/yaml_cpp_adapter.hpp
index a0c5d0a..44fc8a7 100644
--- a/include/valijson/adapters/yaml_cpp_adapter.hpp
+++ b/include/valijson/adapters/yaml_cpp_adapter.hpp
@@ -29,9 +29,9 @@
 #include <yaml-cpp/yaml.h>
 
 #include <utility>
-#include <valijson/adapters/adapter.hpp>
-#include <valijson/adapters/basic_adapter.hpp>
-#include <valijson/adapters/frozen_value.hpp>
+#include <valijson/internal/adapter.hpp>
+#include <valijson/internal/basic_adapter.hpp>
+#include <valijson/internal/frozen_value.hpp>
 #include <valijson/exceptions.hpp>
 
 namespace valijson {
diff --git a/include/valijson/constraints/concrete_constraints.hpp b/include/valijson/constraints/concrete_constraints.hpp
index f6abb63..ebbdfb2 100644
--- a/include/valijson/constraints/concrete_constraints.hpp
+++ b/include/valijson/constraints/concrete_constraints.hpp
@@ -20,9 +20,9 @@
 #include <string>
 #include <vector>
 
-#include <valijson/adapters/frozen_value.hpp>
 #include <valijson/constraints/basic_constraint.hpp>
 #include <valijson/internal/custom_allocator.hpp>
+#include <valijson/internal/frozen_value.hpp>
 #include <valijson/schema.hpp>
 #include <valijson/exceptions.hpp>
 
diff --git a/include/valijson/adapters/adapter.hpp b/include/valijson/internal/adapter.hpp
similarity index 100%
rename from include/valijson/adapters/adapter.hpp
rename to include/valijson/internal/adapter.hpp
diff --git a/include/valijson/adapters/basic_adapter.hpp b/include/valijson/internal/basic_adapter.hpp
similarity index 99%
rename from include/valijson/adapters/basic_adapter.hpp
rename to include/valijson/internal/basic_adapter.hpp
index 84b2abd..a03847c 100644
--- a/include/valijson/adapters/basic_adapter.hpp
+++ b/include/valijson/internal/basic_adapter.hpp
@@ -3,7 +3,7 @@
 #include <cstdint>
 #include <sstream>
 
-#include <valijson/adapters/adapter.hpp>
+#include <valijson/internal/adapter.hpp>
 #include <valijson/internal/optional.hpp>
 #include <valijson/exceptions.hpp>
 
diff --git a/include/valijson/adapters/frozen_value.hpp b/include/valijson/internal/frozen_value.hpp
similarity index 97%
rename from include/valijson/adapters/frozen_value.hpp
rename to include/valijson/internal/frozen_value.hpp
index 56b5eaf..bf8ddc4 100644
--- a/include/valijson/adapters/frozen_value.hpp
+++ b/include/valijson/internal/frozen_value.hpp
@@ -1,6 +1,6 @@
 #pragma once
 
-#include <valijson/adapters/adapter.hpp>
+#include <valijson/internal/adapter.hpp>
 
 namespace valijson {
 namespace adapters {
diff --git a/include/valijson/internal/json_pointer.hpp b/include/valijson/internal/json_pointer.hpp
index b290c02..6328407 100644
--- a/include/valijson/internal/json_pointer.hpp
+++ b/include/valijson/internal/json_pointer.hpp
@@ -7,7 +7,7 @@
 #include <stdexcept>
 #include <string>
 
-#include <valijson/adapters/adapter.hpp>
+#include <valijson/internal/adapter.hpp>
 #include <valijson/internal/optional.hpp>
 #include <valijson/exceptions.hpp>
 
diff --git a/include/valijson/schema_parser.hpp b/include/valijson/schema_parser.hpp
index 05dcfc2..346a93c 100644
--- a/include/valijson/schema_parser.hpp
+++ b/include/valijson/schema_parser.hpp
@@ -6,8 +6,8 @@
 #include <memory>
 #include <functional>
 
-#include <valijson/adapters/adapter.hpp>
 #include <valijson/constraints/concrete_constraints.hpp>
+#include <valijson/internal/adapter.hpp>
 #include <valijson/internal/debug.hpp>
 #include <valijson/internal/json_pointer.hpp>
 #include <valijson/internal/json_reference.hpp>