diff --git a/plugins/VOIP/CMakeLists.txt b/plugins/VOIP/CMakeLists.txt
index bb4448b6f..e86385649 100644
--- a/plugins/VOIP/CMakeLists.txt
+++ b/plugins/VOIP/CMakeLists.txt
@@ -15,7 +15,6 @@ set(CMAKE_AUTORCC ON)
 set(CMAKE_AUTOUIC ON)
 
 # --- Definitions ---
-add_definitions(-D__STDC_CONSTANT_MACROS)
 
 # --- Sources ---
 set(VOIP_SOURCES
@@ -89,6 +88,8 @@ set_target_properties(VOIP PROPERTIES
     AUTOUIC_SEARCH_PATHS "${CMAKE_CURRENT_SOURCE_DIR}/gui"
 )
 
+target_compile_definitions(VOIP PRIVATE __STDC_CONSTANT_MACROS)
+
 # --- Links ---
 
 target_link_libraries(VOIP PRIVATE