diff --git a/CMakeLists.txt b/CMakeLists.txt
index 2cc871a..2b0cfde 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -23,8 +23,6 @@ endif()
 
 enable_testing()
 
-include_directories(".")
-
 add_subdirectory(src/gui)
 add_subdirectory(src/sim)
 add_subdirectory(src/Utils)
diff --git a/src/sim/CMakeLists.txt b/src/sim/CMakeLists.txt
index 72bb603..7706fbf 100644
--- a/src/sim/CMakeLists.txt
+++ b/src/sim/CMakeLists.txt
@@ -4,3 +4,4 @@ add_library(sim
    WindModel.cpp
    USStandardAtmosphere.cpp)
 
+target_include_directories(sim PRIVATE ${PROJECT_SOURCE_DIR}/src)