diff --git a/keywords.txt b/keywords.txt
index 69841fd..41e354d 100644
--- a/keywords.txt
+++ b/keywords.txt
@@ -25,3 +25,4 @@ get_Humidity               KEYWORD2
 AM2302_READ_OK             LITERAL1
 AM2302_ERROR_CHECKSUM      LITERAL1
 AM2302_ERROR_TIMEOUT       LITERAL1
+AM2302_ERROR_READ_FREQ     LITERAL1
diff --git a/library.json b/library.json
index 7fee38d..e81618e 100644
--- a/library.json
+++ b/library.json
@@ -1,6 +1,6 @@
 {
     "name": "AM2302-Sensor",
-    "version": "1.3.0",
+    "version": "1.3.1",
     "repository":
     {
         "type": "git",
diff --git a/library.properties b/library.properties
index d6ce020..b99b2ca 100644
--- a/library.properties
+++ b/library.properties
@@ -1,5 +1,5 @@
 name=AM2302-Sensor
-version=1.3.0
+version=1.3.1
 author=Frank Häfele <mail@frankhaefele.de>
 maintainer=Frank Häfele <mail@frankhaefele.de>
 sentence=This library read temperature and humidity from the AM2302 (aka DHT22) senor.
diff --git a/src/AM2302-Sensor.cpp b/src/AM2302-Sensor.cpp
index f2bcc91..bd6e415 100644
--- a/src/AM2302-Sensor.cpp
+++ b/src/AM2302-Sensor.cpp
@@ -157,7 +157,7 @@ int8_t AM2302::AM2302_Sensor::read_sensor_data(uint8_t *buffer, uint8_t size) {
          // count wait for state time
          while ( !digitalRead(_pin) ) {
             ++wait_counter;
-            delayMicroseconds(1.0);
+            delayMicroseconds(1U);
             if (wait_counter >= READ_TIMEOUT) {
                return AM2302_ERROR_TIMEOUT;
             }
diff --git a/src/AM2302-Sensor.h b/src/AM2302-Sensor.h
index bf08aea..4f728b7 100644
--- a/src/AM2302-Sensor.h
+++ b/src/AM2302-Sensor.h
@@ -22,6 +22,8 @@ namespace AM2302 {
 
    // define timeout in 100 µs
    constexpr uint8_t READ_TIMEOUT         {100U};
+   
+   // define maximum sensor read frequency in milliseconds (2 s)
    constexpr uint16_t READ_FREQUENCY      {2000U};
 
    class AM2302_Sensor {