diff --git a/.github/workflows/arduino_build.yml b/.github/workflows/arduino_build.yml
index 6b5b75a..55f2490 100644
--- a/.github/workflows/arduino_build.yml
+++ b/.github/workflows/arduino_build.yml
@@ -16,6 +16,7 @@ jobs:
           platforms: |
             - name: esp32:esp32
               source-url: https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json
+            - version: 2.0.13
           libraries: |
             - name: Adafruit DotStar
             - name: Sensirion Core
diff --git a/OpenCO2_Sensor.ino b/OpenCO2_Sensor.ino
index aa5dcd5..fff4858 100644
--- a/OpenCO2_Sensor.ino
+++ b/OpenCO2_Sensor.ino
@@ -667,7 +667,7 @@ void loop() {
     errorToString(error, errorMessage, 256);
     displayWriteError(errorMessage);
   } else {
-    extern int refreshes;
+    extern uint16_t refreshes;
     if (BatteryMode || (refreshes%6 == 1)) saveMeasurement(new_co2, new_temperature, humidity);
     /* don't update in Battery mode, unless CO2 has changed by 3% or temperature by 0.5°C */
     if (!TEST_MODE && BatteryMode && comingFromDeepSleep) {
diff --git a/epd_abstraction.ino b/epd_abstraction.ino
index bcb3e3f..05ce9ef 100644
--- a/epd_abstraction.ino
+++ b/epd_abstraction.ino
@@ -50,7 +50,6 @@ void clearMenu() {
 bool buttonPressedAgain = false;
 void handleButtonPress() {
   uint8_t selectedOption = 0;
-  extern uint16_t refreshes;
   refreshes = 1; // force full update
   comingFromDeepSleep = false; // force display update even if CO2 changed by less than 3%
   displayMenu(selectedOption);
@@ -575,7 +574,7 @@ void displayTempHumHistoryGraph() {
     for (int i = 200; i>ytemp; i--) {
       if (!(i%5)) Paint_DrawPoint(x, i, BLACK, DOT_PIXEL_2X2, DOT_FILL_AROUND);
     }
-    Paint_DrawLine(x-1, privYhum, x, yhum, BLACK, DOT_PIXEL_1X1, LINE_STYLE_SOLID);
+    Paint_DrawLine(x-1, privYhum, x, yhum, BLACK, DOT_PIXEL_2X2, LINE_STYLE_SOLID);
     privYtemp = ytemp;
     privYhum = yhum;
   }