diff --git a/external/CMakeLists.txt b/external/CMakeLists.txt
index 8cb70289e..a2a29ce74 100644
--- a/external/CMakeLists.txt
+++ b/external/CMakeLists.txt
@@ -114,7 +114,7 @@ if (LINUX)
     macro(makeCopyFile src dest target)
         if (NOT EXISTS ${dest})
             add_custom_command(TARGET ${target} PRE_BUILD
-                    COMMAND ${CMAKE_COMMAND} -E copy ${src} ${dest} DEPENDS ${dest} COMMENT "copy ${src} -> ${dest}")
+                    COMMAND ${CMAKE_COMMAND} -E copy_if_different ${src} ${dest} DEPENDS ${dest} COMMENT "copy ${src} -> ${dest}")
         endif ()
     endmacro()
 else ()
@@ -138,7 +138,7 @@ else ()
     macro(makeCopy src dest target)
         if (NOT EXISTS ${dest})
             add_custom_command(TARGET ${target} POST_BUILD
-                    COMMAND ${CMAKE_COMMAND} -E copy ${src} ${dest} DEPENDS ${dest} COMMENT "copy ${src} -> ${dest}")
+                    COMMAND ${CMAKE_COMMAND} -E copy_if_different ${src} ${dest} DEPENDS ${dest} COMMENT "copy ${src} -> ${dest}")
         endif ()
     endmacro()
 endif (LINUX)