diff --git a/CHANGELOG.md b/CHANGELOG.md
index 22f33c9d..206cbd50 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@ HEAD
 * Fixed support for `volatile float` and `volatile double` (issue #1557)
 * Fixed error `[Pe070]: incomplete type is not allowed` on IAR (issue #1560)
 * Fixed `serializeJson(doc, String)` when allocation fails (issue #1572)
+* Fixed clang-tidy warnings (issue #1574, PR #1577 by @armandas)
 
 v6.18.0 (2021-05-05)
 -------
diff --git a/README.md b/README.md
index c3002843..090d5549 100644
--- a/README.md
+++ b/README.md
@@ -81,6 +81,7 @@ ArduinoJson is a C++ JSON library for Arduino and IoT (Internet Of Things).
         * [GCC 4.4, 4.6, 4.7, 4.8, 4.9, 5, 6, 7, 8, 9, 10](https://github.com/bblanchon/ArduinoJson/actions?query=workflow%3A%22Continuous+Integration%22)
         * [Clang 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 5.0, 6.0, 7, 8, 9, 10](https://github.com/bblanchon/ArduinoJson/actions?query=workflow%3A%22Continuous+Integration%22)
     * [Continuously fuzzed with Google OSS Fuzz](https://bugs.chromium.org/p/oss-fuzz/issues/list?sort=-opened&can=1&q=proj:arduinojson)
+    * Passes all default checks of [clang-tidy](https://releases.llvm.org/10.0.0/tools/clang/tools/extra/docs/clang-tidy/)
 * Well documented
     * [Tutorials](https://arduinojson.org/v6/doc/deserialization/?utm_source=github&utm_medium=readme)
     * [Examples](https://arduinojson.org/v6/example/?utm_source=github&utm_medium=readme)
diff --git a/extras/tests/.clang-tidy b/extras/tests/.clang-tidy
new file mode 100644
index 00000000..579ae587
--- /dev/null
+++ b/extras/tests/.clang-tidy
@@ -0,0 +1 @@
+Checks:              '-clang-analyzer-security.insecureAPI.*'
diff --git a/src/ArduinoJson/Document/JsonDocument.hpp b/src/ArduinoJson/Document/JsonDocument.hpp
index d67d9349..64c76b8f 100644
--- a/src/ArduinoJson/Document/JsonDocument.hpp
+++ b/src/ArduinoJson/Document/JsonDocument.hpp
@@ -32,7 +32,7 @@ class JsonDocument : public Visitable {
 
   void clear() {
     _pool.clear();
-    _data.setNull();
+    _data.init();
   }
 
   template <typename T>
@@ -304,15 +304,15 @@ class JsonDocument : public Visitable {
 
  protected:
   JsonDocument() : _pool(0, 0) {
-    _data.setNull();
+    _data.init();
   }
 
   JsonDocument(MemoryPool pool) : _pool(pool) {
-    _data.setNull();
+    _data.init();
   }
 
   JsonDocument(char* buf, size_t capa) : _pool(buf, capa) {
-    _data.setNull();
+    _data.init();
   }
 
   ~JsonDocument() {}
diff --git a/src/ArduinoJson/Json/Latch.hpp b/src/ArduinoJson/Json/Latch.hpp
index aef1fe36..70866d6b 100644
--- a/src/ArduinoJson/Json/Latch.hpp
+++ b/src/ArduinoJson/Json/Latch.hpp
@@ -45,7 +45,8 @@ class Latch {
   }
 
   TReader _reader;
-  char _current;
+  char _current;  // NOLINT(clang-analyzer-optin.cplusplus.UninitializedObject)
+                  // Not initialized in constructor (+10 bytes on AVR)
   bool _loaded;
 #if ARDUINOJSON_DEBUG
   bool _ended;
diff --git a/src/ArduinoJson/Json/TextFormatter.hpp b/src/ArduinoJson/Json/TextFormatter.hpp
index 18694f14..7795671f 100644
--- a/src/ArduinoJson/Json/TextFormatter.hpp
+++ b/src/ArduinoJson/Json/TextFormatter.hpp
@@ -155,7 +155,6 @@ class TextFormatter {
 
  protected:
   CountingDecorator<TWriter> _writer;
-  size_t _length;
 
  private:
   TextFormatter &operator=(const TextFormatter &);  // cannot be assigned
diff --git a/src/ArduinoJson/Json/Utf16.hpp b/src/ArduinoJson/Json/Utf16.hpp
index 4e2750f3..00397caf 100644
--- a/src/ArduinoJson/Json/Utf16.hpp
+++ b/src/ArduinoJson/Json/Utf16.hpp
@@ -31,7 +31,7 @@ inline bool isLowSurrogate(uint16_t codeunit) {
 
 class Codepoint {
  public:
-  Codepoint() : _highSurrogate(0) {}
+  Codepoint() : _highSurrogate(0), _codepoint(0) {}
 
   bool append(uint16_t codeunit) {
     if (isHighSurrogate(codeunit)) {
diff --git a/src/ArduinoJson/Memory/MemoryPool.hpp b/src/ArduinoJson/Memory/MemoryPool.hpp
index 49debf85..c8262186 100644
--- a/src/ArduinoJson/Memory/MemoryPool.hpp
+++ b/src/ArduinoJson/Memory/MemoryPool.hpp
@@ -37,7 +37,8 @@ class MemoryPool {
   }
 
   void* buffer() {
-    return _begin;
+    return _begin;  // NOLINT(clang-analyzer-unix.Malloc)
+                    // movePointers() alters this pointer
   }
 
   // Gets the capacity of the memoryPool in bytes
diff --git a/src/ArduinoJson/StringStorage/StringCopier.hpp b/src/ArduinoJson/StringStorage/StringCopier.hpp
index 8b1104b4..80670aad 100644
--- a/src/ArduinoJson/StringStorage/StringCopier.hpp
+++ b/src/ArduinoJson/StringStorage/StringCopier.hpp
@@ -55,8 +55,12 @@ class StringCopier {
 
  private:
   MemoryPool* _pool;
+
+  // These fields aren't initialized by the constructor but startString()
+  //
+  // NOLINTNEXTLINE(clang-analyzer-optin.cplusplus.UninitializedObject)
   char* _ptr;
-  size_t _size;
-  size_t _capacity;
+  // NOLINTNEXTLINE(clang-analyzer-optin.cplusplus.UninitializedObject)
+  size_t _size, _capacity;
 };
 }  // namespace ARDUINOJSON_NAMESPACE
diff --git a/src/ArduinoJson/Variant/VariantData.hpp b/src/ArduinoJson/Variant/VariantData.hpp
index 82ae745d..5631147f 100644
--- a/src/ArduinoJson/Variant/VariantData.hpp
+++ b/src/ArduinoJson/Variant/VariantData.hpp
@@ -33,7 +33,7 @@ class VariantData {
   // - no virtual
   // - no inheritance
   void init() {
-    _flags = 0;
+    _flags = VALUE_IS_NULL;
   }
 
   template <typename TVisitor>