diff --git a/3rdparty/expat/CMakeLists.txt b/3rdparty/expat/CMakeLists.txt
index 550a52c9..badfd61c 100644
--- a/3rdparty/expat/CMakeLists.txt
+++ b/3rdparty/expat/CMakeLists.txt
@@ -1,7 +1,7 @@
 
 configure_file (
     "${PROJECT_SOURCE_DIR}/3rdparty/expat/expat_config_cmake.in"
-    "${PROJECT_BINARY_DIR}/3rdparty/expat/expat_config.h"
+    "${PROJECT_BINARY_DIR}/3rdparty/expat/simgear_expat_config.h"
 )
 
 set(expat_sources 
diff --git a/3rdparty/expat/xmlparse.c b/3rdparty/expat/xmlparse.c
index e4fb313f..83ab782d 100644
--- a/3rdparty/expat/xmlparse.c
+++ b/3rdparty/expat/xmlparse.c
@@ -18,6 +18,8 @@
 #include "amigaconfig.h"
 #elif defined(__WATCOMC__)
 #include "watcomconfig.h"
+#elif defined(HAVE_SIMGEAR_EXPAT_CONFIG_H)
+#include "simgear_expat_config.h"
 #elif defined(HAVE_EXPAT_CONFIG_H)
 #include "expat_config.h"
 #endif /* ndef COMPILED_FROM_DSP */
diff --git a/3rdparty/expat/xmlrole.c b/3rdparty/expat/xmlrole.c
index 0bb159f5..84ce13dd 100644
--- a/3rdparty/expat/xmlrole.c
+++ b/3rdparty/expat/xmlrole.c
@@ -12,6 +12,8 @@
 #include "amigaconfig.h"
 #elif defined(__WATCOMC__)
 #include "watcomconfig.h"
+#elif defined(HAVE_SIMGEAR_EXPAT_CONFIG_H)
+#include "simgear_expat_config.h"
 #else
 #ifdef HAVE_EXPAT_CONFIG_H
 #include "expat_config.h"
diff --git a/3rdparty/expat/xmltok.c b/3rdparty/expat/xmltok.c
index 5a8bd132..674d8cc5 100644
--- a/3rdparty/expat/xmltok.c
+++ b/3rdparty/expat/xmltok.c
@@ -12,6 +12,8 @@
 #include "amigaconfig.h"
 #elif defined(__WATCOMC__)
 #include "watcomconfig.h"
+#elif defined(HAVE_SIMGEAR_EXPAT_CONFIG_H)
+#include "simgear_expat_config.h"
 #else
 #ifdef HAVE_EXPAT_CONFIG_H
 #include "expat_config.h"
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7710db08..705b610d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -273,9 +273,6 @@ if (SYSTEM_EXPAT)
 
 else()
     message(STATUS "Using built-in expat code")
-    # XML_STATIC is important to avoid sg_expat_external.h
-    # declaring symbols as declspec(import)
-    add_definitions(-DHAVE_EXPAT_CONFIG_H -DXML_STATIC)
     set(EXPAT_INCLUDE_DIRS
             ${PROJECT_SOURCE_DIR}/3rdparty/expat
             ${PROJECT_BINARY_DIR}/3rdparty/expat)
diff --git a/simgear/CMakeLists.txt b/simgear/CMakeLists.txt
index ca26c9d2..7646ac09 100644
--- a/simgear/CMakeLists.txt
+++ b/simgear/CMakeLists.txt
@@ -115,11 +115,22 @@ target_include_directories(SimGearCore BEFORE PUBLIC
     $<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}>
     $<INSTALL_INTERFACE:include>)
 
+# so simgear/simgear_config.h is found
+target_include_directories(SimGearCore BEFORE PUBLIC
+    $<BUILD_INTERFACE:${PROJECT_BINARY_DIR}>
+    $<INSTALL_INTERFACE:include>)
+
 target_include_directories(SimGearCore PUBLIC
   ${Boost_INCLUDE_DIRS} ${ZLIB_INCLUDE_DIR})
 target_include_directories(SimGearCore PRIVATE
   ${EXPAT_INCLUDE_DIRS} ${CURL_INCLUDE_DIRS})
 
+if (NOT SYSTEM_EXPAT)
+    # XML_STATIC is important to avoid sg_expat_external.h
+    # declaring symbols as declspec(import)
+    target_compile_definitions(SimGearCore PRIVATE HAVE_SIMGEAR_EXPAT_CONFIG_H XML_STATIC)
+endif()
+
     install(TARGETS SimGearCore
             EXPORT SimGearTargets
             LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
@@ -144,9 +155,10 @@ if (NOT SIMGEAR_HEADLESS)
     endif()
 endif()
 
+# we expose ZLib in some of our headers
+target_link_libraries(SimGearCore PUBLIC ${ZLIB_LIBRARY})
 
-target_link_libraries(SimGearCore
-    ${ZLIB_LIBRARY}
+target_link_libraries(SimGearCore PRIVATE
     ${RT_LIBRARY}
     ${DL_LIBRARY}
     ${CMAKE_THREAD_LIBS_INIT}
@@ -155,29 +167,29 @@ target_link_libraries(SimGearCore
     ${WINSOCK_LIBRARY})
 
 if(SYSTEM_EXPAT)
-    target_link_libraries(SimGearCore
-        ${EXPAT_LIBRARIES})
+    target_link_libraries(SimGearCore PRIVATE ${EXPAT_LIBRARIES})
 endif()
 
 if(ENABLE_DNS AND SYSTEM_UDNS)
-    target_link_libraries(SimGearCore
-        ${UDNS_LIBRARIES})
+    target_link_libraries(SimGearCore PRIVATE ${UDNS_LIBRARIES})
 endif()
 
 if(NOT SIMGEAR_HEADLESS)
     target_include_directories(SimGearScene PRIVATE ${PROJECT_SOURCE_DIR}/simgear/canvas/ShivaVG/include)
 
-    target_link_libraries(SimGearScene
+    target_link_libraries(SimGearScene PUBLIC         
         SimGearCore
-        ${ZLIB_LIBRARY}
         ${OPENSCENEGRAPH_LIBRARIES}
+    )
+
+    target_link_libraries(SimGearScene PRIVATE
+        ${ZLIB_LIBRARY}
         ${OPENAL_LIBRARY}
         ${OPENGL_LIBRARY}
         ${JPEG_LIBRARY})
 
     if(ENABLE_GDAL)
-        target_link_libraries(SimGearScene
-            ${GDAL_LIBRARIES})
+        target_link_libraries(SimGearScene PRIVATE ${GDAL_LIBRARIES})
     endif()
 
     # only actually needed by canvas/KeyboardEvent.cxx