diff --git a/CMakeLists.txt b/CMakeLists.txt
index bab4819e..18f5f7ac 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -213,7 +213,7 @@ IF(VMIME_BUILD_STATIC_LIBRARY)
 ENDIF()
 
 # Installation of header files
-INSTALL_HEADERS_WITH_DIRECTORY(VMIME_LIBRARY_INCLUDE_FILES headers "${CMAKE_SOURCE_DIR}/src/")
+INSTALL_HEADERS_WITH_DIRECTORY(VMIME_LIBRARY_INCLUDE_FILES headers "${CMAKE_CURRENT_SOURCE_DIR}/src/")
 INSTALL_HEADERS_WITH_DIRECTORY(VMIME_LIBRARY_GENERATED_INCLUDE_FILES headers "${CMAKE_BINARY_DIR}/src")
 
 #INSTALL(
@@ -242,12 +242,12 @@ IF(VMIME_BUILD_TESTS)
 	FILE(
 		GLOB_RECURSE
 		VMIME_TESTS_SRC_FILES
-		${CMAKE_SOURCE_DIR}/tests/*Test.cpp
+		${CMAKE_CURRENT_SOURCE_DIR}/tests/*Test.cpp
 	)
 
 	ADD_LIBRARY(
 		test-runner
-		${CMAKE_SOURCE_DIR}/tests/testRunner.cpp ${CMAKE_SOURCE_DIR}/tests/testUtils.cpp
+		${CMAKE_CURRENT_SOURCE_DIR}/tests/testRunner.cpp ${CMAKE_CURRENT_SOURCE_DIR}/tests/testUtils.cpp
 	)
 
 	# Build one file for each test
@@ -255,7 +255,7 @@ IF(VMIME_BUILD_TESTS)
 
 		# "/path/to/vmime/tests/module/testFile.cpp" --> "module_testFile"
 		GET_FILENAME_COMPONENT(VMIME_TEST_SRC_PATH "${VMIME_TEST_SRC_FILE}" PATH)
-		STRING(REPLACE "${CMAKE_SOURCE_DIR}" "" VMIME_TEST_SRC_PATH "${VMIME_TEST_SRC_PATH}")
+		STRING(REPLACE "${CMAKE_CURRENT_SOURCE_DIR}" "" VMIME_TEST_SRC_PATH "${VMIME_TEST_SRC_PATH}")
 		GET_FILENAME_COMPONENT(VMIME_TEST_NAME "${VMIME_TEST_SRC_FILE}" NAME_WE)
 		SET(VMIME_TEST_NAME "${VMIME_TEST_SRC_PATH}/${VMIME_TEST_NAME}")
 		STRING(REPLACE "/" "_" VMIME_TEST_NAME "${VMIME_TEST_NAME}")
@@ -330,15 +330,15 @@ SET(CPACK_PACKAGE_DESCRIPTION_SUMMARY  "${CPACK_PACKAGE_DESCRIPTION}")
 SET(CPACK_PACKAGE_VERSION              "${VMIME_PACKAGE_VERSION}")
 
 # Package settings
-SET(CPACK_RESOURCE_FILE_LICENSE        ${CMAKE_SOURCE_DIR}/COPYING)
+SET(CPACK_RESOURCE_FILE_LICENSE        ${CMAKE_CURRENT_SOURCE_DIR}/COPYING)
 
 IF(APPLE)
 	# CPack/PackageManager won't allow file without recognized extension
 	# to be used as license file.
-	CONFIGURE_FILE("${CMAKE_SOURCE_DIR}/COPYING" "${CMAKE_BINARY_DIR}/COPYING.txt" COPYONLY)
+	CONFIGURE_FILE("${CMAKE_CURRENT_SOURCE_DIR}/COPYING" "${CMAKE_BINARY_DIR}/COPYING.txt" COPYONLY)
 	SET(CPACK_RESOURCE_FILE_LICENSE "${CMAKE_BINARY_DIR}/COPYING.txt")
 ELSE()
-	SET(CPACK_RESOURCE_FILE_LICENSE "${CMAKE_SOURCE_DIR}/COPYING")
+	SET(CPACK_RESOURCE_FILE_LICENSE "${CMAKE_CURRENT_SOURCE_DIR}/COPYING")
 ENDIF(APPLE)
 
 SET(CPACK_SOURCE_GENERATOR             TGZ)
@@ -372,7 +372,7 @@ ADD_CUSTOM_TARGET(
 	dist
 	COMMAND git archive --prefix=${ARCHIVE_NAME}/ HEAD
 	| bzip2 > ${CMAKE_BINARY_DIR}/${ARCHIVE_NAME}.tar.bz2
-	WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
+	WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
 )
 
 # PkgConfig
@@ -1039,7 +1039,7 @@ IF(VMIME_BUILD_DOCUMENTATION)
 	FIND_PACKAGE(Doxygen)
 
 	IF(DOXYGEN_FOUND)
-		CONFIGURE_FILE(${CMAKE_SOURCE_DIR}/Doxyfile.in ${CMAKE_BINARY_DIR}/Doxyfile @ONLY)
+		CONFIGURE_FILE(${CMAKE_CURRENT_SOURCE_DIR}/Doxyfile.in ${CMAKE_BINARY_DIR}/Doxyfile @ONLY)
 
 		# Make a target so that documentation can be generated by running "make doc"
 		ADD_CUSTOM_TARGET(
@@ -1084,7 +1084,7 @@ ENDIF()
 CONFIGURE_FILE(cmake/config.hpp.cmake ${CMAKE_BINARY_DIR}/src/vmime/config.hpp)
 
 # PkgConfig post-configuration
-CONFIGURE_FILE(${CMAKE_SOURCE_DIR}/vmime.pc.in ${CMAKE_BINARY_DIR}/vmime.pc @ONLY)
+CONFIGURE_FILE(${CMAKE_CURRENT_SOURCE_DIR}/vmime.pc.in ${CMAKE_BINARY_DIR}/vmime.pc @ONLY)
 INSTALL(FILES ${CMAKE_BINARY_DIR}/vmime.pc DESTINATION "${CMAKE_INSTALL_PREFIX}/${CMAKE_INSTALL_LIBDIR}/pkgconfig" COMPONENT headers)
 
 INCLUDE(CPack)