diff --git a/CMakeLists.txt b/CMakeLists.txt
index 43126d48..8476da63 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -207,17 +207,14 @@ else()
     if (ENABLE_SOUND)
         if (USE_AEONWAVE)
             find_package(AAX COMPONENTS aax REQUIRED)
-            include_directories( ${AAX_INCLUDE_DIR} )
         else()
             find_package(OpenAL REQUIRED)
-            include_directories( ${OPENAL_INCLUDE_DIR} )
         endif()
 
         message(STATUS "Sound support: ENABLED")
     endif(ENABLE_SOUND)
 
     find_package(OpenSceneGraph 3.2.0 REQUIRED osgText osgSim osgDB osgParticle osgGA osgViewer osgUtil)
-    include_directories(${OPENSCENEGRAPH_INCLUDE_DIRS})
 
     if (MSVC)
       set(CMAKE_REQUIRED_INCLUDES ${OPENSCENEGRAPH_INCLUDE_DIRS})
@@ -253,8 +250,6 @@ else()
 	    ${PROJECT_BINARY_DIR}/3rdparty/expat)
 endif(SYSTEM_EXPAT)
 
-include_directories(${EXPAT_INCLUDE_DIRS})
-
 check_include_file(inttypes.h HAVE_INTTYPES_H)
 check_include_file(sys/time.h HAVE_SYS_TIME_H)
 check_include_file(sys/timeb.h HAVE_SYS_TIMEB_H)
@@ -413,12 +408,6 @@ set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${MSVC_LD_FLAGS}")
 # ahead of system-installed libs
 include_directories(BEFORE ${PROJECT_BINARY_DIR}/simgear)
 
-include_directories(
-    ${Boost_INCLUDE_DIRS}
-    ${ZLIB_INCLUDE_DIR}
-    ${CURL_INCLUDE_DIRS}
-)
-
 add_definitions(-DHAVE_CONFIG_H)
 
 # configure a header file to pass some of the CMake settings
diff --git a/simgear/CMakeLists.txt b/simgear/CMakeLists.txt
index 1759d7a5..27fb6bac 100644
--- a/simgear/CMakeLists.txt
+++ b/simgear/CMakeLists.txt
@@ -112,6 +112,12 @@ target_include_directories(SimGearCore BEFORE PUBLIC
     $<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}>
     $<INSTALL_INTERFACE:include>)
 
+target_include_directories(SimGearCore PUBLIC ${Boost_INCLUDE_DIRS})
+target_include_directories(SimGearCore PRIVATE
+  ${EXPAT_INCLUDE_DIRS}
+  ${ZLIB_INCLUDE_DIR}
+  ${CURL_INCLUDE_DIRS})
+
     install(TARGETS SimGearCore
             EXPORT SimGearTargets
             LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
@@ -127,6 +133,13 @@ if (NOT SIMGEAR_HEADLESS)
       $<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}>
     $<INSTALL_INTERFACE:include>)
 
+    target_include_directories(SimGearScene PUBLIC ${OPENSCENEGRAPH_INCLUDE_DIRS})
+
+    if (USE_AEONWAVE)
+      target_include_directories(SimGearScene PRIVATE ${AAX_INCLUDE_DIR} )
+    else()
+      target_include_directories(SimGearScene PRIVATE ${OPENAL_INCLUDE_DIR} )
+    endif()
 endif()