diff --git a/src/OpenMesh/Core/CMakeLists.txt b/src/OpenMesh/Core/CMakeLists.txt
index cc3a73fb..abe7a101 100644
--- a/src/OpenMesh/Core/CMakeLists.txt
+++ b/src/OpenMesh/Core/CMakeLists.txt
@@ -133,7 +133,7 @@ install(DIRECTORY IO/
 endif ()
 
 target_include_directories(OpenMeshCore PUBLIC
-  $<BUILD_INTERFACE:${CMAKE_SOURCE_DIR}/src>
+  $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/../..>
   $<INSTALL_INTERFACE:include>)
 
 install(TARGETS OpenMeshCore EXPORT OpenMeshConfig
diff --git a/src/OpenMesh/Tools/CMakeLists.txt b/src/OpenMesh/Tools/CMakeLists.txt
index b48530a0..fcba8a94 100644
--- a/src/OpenMesh/Tools/CMakeLists.txt
+++ b/src/OpenMesh/Tools/CMakeLists.txt
@@ -116,7 +116,7 @@ install(FILES Utils/getopt.h DESTINATION include/OpenMesh/Tools/Utils)
 endif ()
 
 target_include_directories(OpenMeshTools PUBLIC
-  $<BUILD_INTERFACE:${CMAKE_SOURCE_DIR}/src>
+  $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/../..>
   $<INSTALL_INTERFACE:include>)
 
 install(TARGETS OpenMeshTools EXPORT OpenMeshConfig