diff --git a/CMakeLists.txt b/CMakeLists.txt
index 38c800608..7bbfb201a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -5,6 +5,8 @@ else()
     project("mbed TLS" C)
 endif()
 
+set(MBEDTLS_DIR ${CMAKE_CURRENT_SOURCE_DIR})
+
 option(USE_PKCS11_HELPER_LIBRARY "Build mbed TLS with the pkcs11-helper library." OFF)
 option(ENABLE_ZLIB_SUPPORT "Build mbed TLS with zlib library." OFF)
 
diff --git a/library/CMakeLists.txt b/library/CMakeLists.txt
index 1004cb30b..7f0819ef6 100644
--- a/library/CMakeLists.txt
+++ b/library/CMakeLists.txt
@@ -151,15 +151,15 @@ if(USE_STATIC_MBEDTLS_LIBRARY)
     set_target_properties(${mbedx509_static_target} PROPERTIES OUTPUT_NAME mbedx509)
     target_link_libraries(${mbedx509_static_target} ${libs} ${mbedcrypto_static_target})
     target_include_directories(${mbedx509_static_target}
-        PUBLIC ${CMAKE_SOURCE_DIR}/include/
-        PUBLIC ${CMAKE_SOURCE_DIR}/crypto/include/)
+        PUBLIC ${MBEDTLS_DIR}/include/
+        PUBLIC ${MBEDTLS_DIR}/crypto/include/)
 
     add_library(${mbedtls_static_target} STATIC ${src_tls})
     set_target_properties(${mbedtls_static_target} PROPERTIES OUTPUT_NAME mbedtls)
     target_link_libraries(${mbedtls_static_target} ${libs} ${mbedx509_static_target})
     target_include_directories(${mbedtls_static_target}
-        PUBLIC ${CMAKE_SOURCE_DIR}/include/
-        PUBLIC ${CMAKE_SOURCE_DIR}/crypto/include/
+        PUBLIC ${MBEDTLS_DIR}/include/
+        PUBLIC ${MBEDTLS_DIR}/crypto/include/
         )
 
 
@@ -175,15 +175,15 @@ if(USE_SHARED_MBEDTLS_LIBRARY)
     set_target_properties(mbedx509 PROPERTIES VERSION 2.17.0 SOVERSION 0)
     target_link_libraries(mbedx509 ${libs} mbedcrypto)
     target_include_directories(mbedx509
-        PUBLIC ${CMAKE_SOURCE_DIR}/include/
-        PUBLIC ${CMAKE_SOURCE_DIR}/crypto/include/)
+        PUBLIC ${MBEDTLS_DIR}/include/
+        PUBLIC ${MBEDTLS_DIR}/crypto/include/)
 
     add_library(mbedtls SHARED ${src_tls})
     set_target_properties(mbedtls PROPERTIES VERSION 2.17.0 SOVERSION 12)
     target_link_libraries(mbedtls ${libs} mbedx509)
     target_include_directories(mbedtls
-        PUBLIC ${CMAKE_SOURCE_DIR}/include/
-        PUBLIC ${CMAKE_SOURCE_DIR}/crypto/include/)
+        PUBLIC ${MBEDTLS_DIR}/include/
+        PUBLIC ${MBEDTLS_DIR}/crypto/include/)
 
       install(TARGETS mbedtls mbedx509
               DESTINATION ${LIB_INSTALL_DIR}