diff --git a/include/ArduinoJson/Internals/JsonWriter.hpp b/include/ArduinoJson/Internals/JsonWriter.hpp
index dca48963..b19dbe27 100644
--- a/include/ArduinoJson/Internals/JsonWriter.hpp
+++ b/include/ArduinoJson/Internals/JsonWriter.hpp
@@ -28,7 +28,7 @@ class JsonWriter {
   void writeString(const char *value);
   void writeInteger(long value);
   void writeBoolean(bool value);
-  void writeDouble(double value, int decimals);
+  void writeDouble(double value, uint8_t decimals);
 
   void writeColon() { _length += _sink->write(':'); }
   void writeComma() { _length += _sink->write(','); }
diff --git a/include/ArduinoJson/JsonArray.hpp b/include/ArduinoJson/JsonArray.hpp
index 8c94f131..d2d596a1 100644
--- a/include/ArduinoJson/JsonArray.hpp
+++ b/include/ArduinoJson/JsonArray.hpp
@@ -41,7 +41,7 @@ class JsonArray : public JsonPrintable<JsonArray>,
   }
 
   value_type &add();
-  void add(double value, int decimals) { add().set(value, decimals); }
+  void add(double value, uint8_t decimals) { add().set(value, decimals); }
   void add(JsonArray &nestedArray) { add().set(nestedArray); }
   void add(JsonObject &nestedObject) { add().set(nestedObject); }
 
diff --git a/include/ArduinoJson/JsonValue.hpp b/include/ArduinoJson/JsonValue.hpp
index 0591bc0a..8cfe4d6d 100644
--- a/include/ArduinoJson/JsonValue.hpp
+++ b/include/ArduinoJson/JsonValue.hpp
@@ -7,6 +7,7 @@
 #pragma once
 
 #include <stddef.h>
+#include <stdint.h>  // for uint8_t
 
 #include "Internals/JsonValueContent.hpp"
 #include "Internals/JsonValueType.hpp"
@@ -25,7 +26,7 @@ class JsonValue {
   JsonValue() : _type(Internals::JSON_UNDEFINED) {}
 
   void set(bool value);
-  void set(double value, int decimals = 2);
+  void set(double value, uint8_t decimals = 2);
   void set(signed char value) { set(static_cast<long>(value)); }
   void set(signed int value) { set(static_cast<long>(value)); }
   void set(signed long value);
diff --git a/src/Internals/JsonParser.cpp b/src/Internals/JsonParser.cpp
index 1df73876..9d6ef761 100644
--- a/src/Internals/JsonParser.cpp
+++ b/src/Internals/JsonParser.cpp
@@ -118,7 +118,7 @@ void JsonParser::parseNumberTo(JsonValue &destination) {
   if (*endOfLong == '.') {
     // stopped on a decimal separator
     double doubleValue = strtod(_ptr, &_ptr);
-    int decimals = _ptr - endOfLong - 1;
+    uint8_t decimals = _ptr - endOfLong - 1;
     destination.set(doubleValue, decimals);
   } else {
     _ptr = endOfLong;
diff --git a/src/Internals/JsonWriter.cpp b/src/Internals/JsonWriter.cpp
index e1ae73d3..9054cd95 100644
--- a/src/Internals/JsonWriter.cpp
+++ b/src/Internals/JsonWriter.cpp
@@ -19,6 +19,6 @@ void JsonWriter::writeBoolean(bool value) {
   _length += _sink->print(value ? "true" : "false");
 }
 
-void JsonWriter::writeDouble(double value, int decimals) {
+void JsonWriter::writeDouble(double value, uint8_t decimals) {
   _length += _sink->print(value, decimals);
 }
diff --git a/src/JsonValue.cpp b/src/JsonValue.cpp
index ab44d396..ddb81acf 100644
--- a/src/JsonValue.cpp
+++ b/src/JsonValue.cpp
@@ -50,7 +50,7 @@ void JsonValue::set(const char *value) {
   _content.asString = value;
 }
 
-void JsonValue::set(double value, int decimals) {
+void JsonValue::set(double value, uint8_t decimals) {
   if (_type == JSON_INVALID) return;
   _type = static_cast<JsonValueType>(JSON_DOUBLE_0_DECIMALS + decimals);
   _content.asDouble = value;