diff --git a/mkspecs/freebsd-clang/qmake.conf b/mkspecs/freebsd-clang/qmake.conf
index 6064cd23..1a56e989 100644
--- a/mkspecs/freebsd-clang/qmake.conf
+++ b/mkspecs/freebsd-clang/qmake.conf
@@ -12,7 +12,7 @@ QMAKE_LEX		= flex
 QMAKE_LEXFLAGS		=
 QMAKE_YACC		= yacc
 QMAKE_YACCFLAGS		= -d
-QMAKE_CFLAGS		= -pipe
+QMAKE_CFLAGS		= -pipe -fvisibility=hidden -fvisibility-inlines-hidden
 QMAKE_CFLAGS_DEPS	= -M
 QMAKE_CFLAGS_WARN_ON	= -Wall -W
 QMAKE_CFLAGS_WARN_OFF	= -w
diff --git a/mkspecs/freebsd-g++/qmake.conf b/mkspecs/freebsd-g++/qmake.conf
index 60ca7e36..289e31e4 100644
--- a/mkspecs/freebsd-g++/qmake.conf
+++ b/mkspecs/freebsd-g++/qmake.conf
@@ -12,7 +12,7 @@ QMAKE_LEX		= flex
 QMAKE_LEXFLAGS		= 
 QMAKE_YACC		= yacc
 QMAKE_YACCFLAGS		= -d
-QMAKE_CFLAGS		= -pipe
+QMAKE_CFLAGS		= -pipe -fvisibility=hidden -fvisibility-inlines-hidden
 QMAKE_CFLAGS_DEPS	= -M
 QMAKE_CFLAGS_WARN_ON	= -Wall -W
 QMAKE_CFLAGS_WARN_OFF	= -w
diff --git a/mkspecs/netbsd-g++/qmake.conf b/mkspecs/netbsd-g++/qmake.conf
index b5975dd0..7056112d 100644
--- a/mkspecs/netbsd-g++/qmake.conf
+++ b/mkspecs/netbsd-g++/qmake.conf
@@ -12,7 +12,7 @@ QMAKE_LEX		= flex
 QMAKE_LEXFLAGS		= 
 QMAKE_YACC		= yacc
 QMAKE_YACCFLAGS		= -d
-QMAKE_CFLAGS		= -pipe
+QMAKE_CFLAGS		= -pipe -fvisibility=hidden -fvisibility-inlines-hidden
 QMAKE_CFLAGS_DEPS	= -M
 QMAKE_CFLAGS_WARN_ON	= -Wall -W
 QMAKE_CFLAGS_WARN_OFF	= -w
diff --git a/mkspecs/openbsd-g++/qmake.conf b/mkspecs/openbsd-g++/qmake.conf
index 01aa46c4..2783f2f7 100644
--- a/mkspecs/openbsd-g++/qmake.conf
+++ b/mkspecs/openbsd-g++/qmake.conf
@@ -12,7 +12,7 @@ QMAKE_LEX		= flex
 QMAKE_LEXFLAGS		= 
 QMAKE_YACC		= yacc
 QMAKE_YACCFLAGS		= -d
-QMAKE_CFLAGS		= -pipe
+QMAKE_CFLAGS		= -pipe -fvisibility=hidden -fvisibility-inlines-hidden
 QMAKE_CFLAGS_DEPS	= -M
 QMAKE_CFLAGS_WARN_ON	= -Wall -W
 QMAKE_CFLAGS_WARN_OFF	= -w