diff --git a/Makefile b/Makefile
index 21ced680df5b357dcb0c0509f789d3dda862f3c9..5694a17913fd98370f47c32eb493a4ef9f478f64 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 NAME_SRV = socket2-srv
 
-CXXFLAGS =
-LDFLAGS =
+CXXFLAGS +=
+LDFLAGS +=
 
 include ../makefiles/Make-9.3.3.in