diff -up libical-3.0.3/CMakeLists.txt.cmake-version libical-3.0.3/CMakeLists.txt
--- libical-3.0.3/CMakeLists.txt.cmake-version	2018-02-27 16:34:25.000000000 +0100
+++ libical-3.0.3/CMakeLists.txt	2018-05-31 16:31:14.858002781 +0200
@@ -70,7 +70,7 @@
 #  Build with the thread sanitizer (requires gcc or clang)
 #
 
-cmake_minimum_required(VERSION 3.1.0) #first line, to shutup a cygwin warning
+cmake_minimum_required(VERSION 2.8.0) #first line, to shutup a cygwin warning
 project(libical C CXX)
 
 cmake_policy(SET CMP0003 NEW)
diff -up libical-3.0.3/cmake/modules/GObjectIntrospectionMacros.cmake.cmake-version libical-3.0.3/cmake/modules/GObjectIntrospectionMacros.cmake
--- libical-3.0.3/cmake/modules/GObjectIntrospectionMacros.cmake.cmake-version	2018-05-31 16:59:07.730979648 +0200
+++ libical-3.0.3/cmake/modules/GObjectIntrospectionMacros.cmake	2018-05-31 17:03:01.110976420 +0200
@@ -50,7 +50,7 @@ macro(gir_add_introspections introspecti
     set(_gir_libtool "--no-libtool")
 
     add_custom_command(
-      COMMAND ${CMAKE_COMMAND} -E env "CC='${CMAKE_C_COMPILER}'"
+      COMMAND
               ${GObjectIntrospection_SCANNER}
               ${GObjectIntrospection_SCANNER_ARGS}
               --namespace=${_gir_namespace}