diff --git a/tests/scripts/key-exchanges.pl b/tests/scripts/key-exchanges.pl
index 9e35cfa..46826c3 100755
--- a/tests/scripts/key-exchanges.pl
+++ b/tests/scripts/key-exchanges.pl
@@ -35,7 +35,7 @@
             and abort "Failed to disable $k\n";
     }
 
-    system( "make lib" ) and abort "Failed to build lib: $kex\n";
+    system( "make lib CFLAGS='-Os -Werror'" ) and abort "Failed to build lib: $kex\n";
 }
 
 system( "mv $config_h.bak $config_h" ) and die "$config_h not restored\n";