diff --git a/arduino-core/src/cc/arduino/Constants.java b/arduino-core/src/cc/arduino/Constants.java
index 8d67f6ed9f1..67e3a4f82d3 100644
--- a/arduino-core/src/cc/arduino/Constants.java
+++ b/arduino-core/src/cc/arduino/Constants.java
@@ -74,7 +74,7 @@ public class Constants {
     if (extenalPackageIndexUrl != null && !"".equals(extenalPackageIndexUrl)) {
       PACKAGE_INDEX_URL = extenalPackageIndexUrl;
     } else {
-      PACKAGE_INDEX_URL = "http://downloads.arduino.cc/packages/package_index.json";
+      PACKAGE_INDEX_URL = "https://downloads.arduino.cc/packages/package_index.json";
     }
 
     String externalLibraryIndexUrl = System.getProperty("LIBRARY_INDEX_URL");
@@ -87,8 +87,8 @@ public class Constants {
         LIBRARY_INDEX_URL_GZ = "";
       }
     } else {
-      LIBRARY_INDEX_URL = "http://downloads.arduino.cc/libraries/library_index.json";
-      LIBRARY_INDEX_URL_GZ = "http://downloads.arduino.cc/libraries/library_index.json.gz";
+      LIBRARY_INDEX_URL = "https://downloads.arduino.cc/libraries/library_index.json";
+      LIBRARY_INDEX_URL_GZ = "https://downloads.arduino.cc/libraries/library_index.json.gz";
     }
   }