diff --git a/tools/assimp_cmd/CMakeLists.txt b/tools/assimp_cmd/CMakeLists.txt
index e6f34fefb..899a8e02a 100644
--- a/tools/assimp_cmd/CMakeLists.txt
+++ b/tools/assimp_cmd/CMakeLists.txt
@@ -22,7 +22,8 @@ SET_PROPERTY(TARGET assimp_cmd PROPERTY DEBUG_POSTFIX ${ASSIMP_DEBUG_POSTFIX})
 IF( WIN32 )
 	ADD_CUSTOM_COMMAND(TARGET assimp_cmd
 		PRE_BUILD
-		COMMAND ${CMAKE_COMMAND} -E copy_if_different $<TARGET_FILE:assimp> $<TARGET_FILE_DIR:assimp_cmd>)
+		COMMAND ${CMAKE_COMMAND} -E copy_if_different $<TARGET_FILE:assimp> $<TARGET_FILE_DIR:assimp_cmd>
+		MAIN_DEPENDENCY assimp)
 ENDIF( WIN32 )
 
 TARGET_LINK_LIBRARIES( assimp_cmd assimp ${ZLIB_LIBRARIES})
diff --git a/tools/assimp_view/CMakeLists.txt b/tools/assimp_view/CMakeLists.txt
index 167601b24..655a38571 100644
--- a/tools/assimp_view/CMakeLists.txt
+++ b/tools/assimp_view/CMakeLists.txt
@@ -50,7 +50,8 @@ ADD_DEFINITIONS( -D_CRT_SECURE_NO_WARNINGS )
 #
 ADD_CUSTOM_COMMAND(TARGET assimp_viewer 
 	PRE_BUILD
-	COMMAND ${CMAKE_COMMAND} -E copy_if_different $<TARGET_FILE:assimp> $<TARGET_FILE_DIR:assimp_viewer>)
+	COMMAND ${CMAKE_COMMAND} -E copy_if_different $<TARGET_FILE:assimp> $<TARGET_FILE_DIR:assimp_viewer>
+	MAIN_DEPENDENCY assimp)
 
 # Link the executable to the assimp + dx libs.
 TARGET_LINK_LIBRARIES ( assimp_viewer assimp ${DirectX_LIBRARY} ${DirectX_D3DX9_LIBRARY} comctl32.lib Winmm.lib  )