diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index cc5952c..bdf0414 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -108,7 +108,6 @@ target_include_directories(fmi4cpp
         $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/../include>
     PRIVATE
         "${CMAKE_CURRENT_SOURCE_DIR}"
-        "${CMAKE_CURRENT_SOURCE_DIR}/external/pugixml"
 )
 
 if (FMI4CPP_USE_EXTERNAL_PUGIXML)
@@ -116,6 +115,11 @@ if (FMI4CPP_USE_EXTERNAL_PUGIXML)
         PRIVATE
             pugixml::pugixml
     )
+else ()
+    target_include_directories(fmi4cpp
+        PRIVATE
+            "${CMAKE_CURRENT_SOURCE_DIR}/external/pugixml"
+    )
 endif ()
 
 if(WIN32)