diff --git a/mkspecs/dilos-g++/qmake.conf b/mkspecs/dilos-g++/qmake.conf
index d7d634eb..bab350f0 100644
--- a/mkspecs/dilos-g++/qmake.conf
+++ b/mkspecs/dilos-g++/qmake.conf
@@ -16,7 +16,7 @@ QMAKE_YACCFLAGS		= -d
 QMAKE_YACCFLAGS_MANGLE  = -p $base -b $base
 QMAKE_YACC_HEADER       = $base.tab.h
 QMAKE_YACC_SOURCE       = $base.tab.c
-QMAKE_CFLAGS		= -pipe -D__dilos__ -D__EXTENSIONS__
+QMAKE_CFLAGS		= -pipe -D__dilos__ -D__EXTENSIONS__ -fvisibility=hidden -fvisibility-inlines-hidden
 QMAKE_CFLAGS_DEPS	= -M
 QMAKE_CFLAGS_WARN_ON	= -Wall -W
 QMAKE_CFLAGS_WARN_OFF	= -w