diff --git a/tools/assimp_cmd/Main.h b/tools/assimp_cmd/Main.h
index 01bd74530..96b0684c3 100644
--- a/tools/assimp_cmd/Main.h
+++ b/tools/assimp_cmd/Main.h
@@ -46,7 +46,9 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #ifndef AICMD_MAIN_INCLUDED
 #define AICMD_MAIN_INCLUDED
 
+#ifndef _CRT_SECURE_NO_WARNINGS
 #define _CRT_SECURE_NO_WARNINGS
+#endif
 
 #include <stdio.h>
 #include <string.h>
@@ -203,4 +205,4 @@ int Assimp_TestBatchLoad (
 	unsigned int num);
 
 
-#endif // !! AICMD_MAIN_INCLUDED
\ No newline at end of file
+#endif // !! AICMD_MAIN_INCLUDED