diff --git a/core/main.mk b/core/main.mk
index 15e8973..c22c967 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -45,7 +45,7 @@
 $(warning ********************************************************************************)
 $(warning *  You are using version $(MAKE_VERSION) of make.)
 $(warning *  Android can only be built by versions 3.81 and 3.82.)
-$(warning *  see http://source.android.com/source/download.html)
+$(warning *  see https://source.android.com/source/download.html)
 $(warning ********************************************************************************)
 $(error stopping)
 endif
@@ -131,7 +131,7 @@
 $(info The correct version is: Java SE 1.6.)
 $(info $(space))
 $(info Please follow the machine setup instructions at)
-$(info $(space)$(space)$(space)$(space)http://source.android.com/source/download.html)
+$(info $(space)$(space)$(space)$(space)https://source.android.com/source/download.html)
 $(info ************************************************************)
 $(error stop)
 endif
@@ -147,7 +147,7 @@
 $(info The correct version is: 1.6.)
 $(info $(space))
 $(info Please follow the machine setup instructions at)
-$(info $(space)$(space)$(space)$(space)http://source.android.com/source/download.html)
+$(info $(space)$(space)$(space)$(space)https://source.android.com/source/download.html)
 $(info ************************************************************)
 $(error stop)
 endif