diff --git a/acinclude.m4 b/acinclude.m4
index 624b393..30169ac 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -3222,8 +3222,8 @@ AC_DEFUN([AC_CHECK_COMPILERS],
         CXXFLAGS="-Wall -W -Wpointer-arith $CXXFLAGS"
         case $host in
           *-*-linux-gnu)	
-            CFLAGS="-std=iso9899:1990 -W -Wall -Wchar-subscripts -Wshadow -Wpointer-arith -Wmissing-prototypes -Wwrite-strings -D_XOPEN_SOURCE=500 -D_BSD_SOURCE $CFLAGS"
-            CXXFLAGS="-ansi -D_XOPEN_SOURCE=500 -D_BSD_SOURCE -Wcast-align -Wchar-subscripts $CXXFLAGS"
+            CFLAGS="-std=iso9899:1990 -W -Wall -Wchar-subscripts -Wshadow -Wpointer-arith -Wmissing-prototypes -Wwrite-strings -D_XOPEN_SOURCE=500 -D_DEFAULT_SOURCE $CFLAGS"
+            CXXFLAGS="-ansi -D_XOPEN_SOURCE=500 -D_DEFAULT_SOURCE -Wcast-align -Wchar-subscripts $CXXFLAGS"
             KDE_CHECK_COMPILER_FLAG(Wmissing-format-attribute, [CXXFLAGS="$CXXFLAGS -Wformat-security -Wmissing-format-attribute"])
             KDE_CHECK_C_COMPILER_FLAG(Wmissing-format-attribute, [CFLAGS="$CFLAGS -Wformat-security -Wmissing-format-attribute"])
           ;;