diff --git a/examples/stm32/f0/stm32f0-discovery/usart_stdio/usart_stdio.c b/examples/stm32/f0/stm32f0-discovery/usart_stdio/usart_stdio.c
index 0f15aea..012786d 100644
--- a/examples/stm32/f0/stm32f0-discovery/usart_stdio/usart_stdio.c
+++ b/examples/stm32/f0/stm32f0-discovery/usart_stdio/usart_stdio.c
@@ -18,6 +18,7 @@
  * along with this library.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#define _GNU_SOURCE
 #include <libopencm3/stm32/rcc.h>
 #include <libopencm3/stm32/gpio.h>
 #include <libopencm3/stm32/usart.h>
diff --git a/examples/stm32/f4/stm32f429i-discovery/lcd-dma/console.c b/examples/stm32/f4/stm32f429i-discovery/lcd-dma/console.c
index e6bc91e..9534169 100644
--- a/examples/stm32/f4/stm32f429i-discovery/lcd-dma/console.c
+++ b/examples/stm32/f4/stm32f429i-discovery/lcd-dma/console.c
@@ -22,6 +22,7 @@
  *
  */
 
+#define _GNU_SOURCE
 #include <stdint.h>
 #include <stdio.h>
 #include <setjmp.h>