diff --git a/lib/stm32/f1/gpio.c b/lib/stm32/f1/gpio.c
index 06020125..e513d29e 100644
--- a/lib/stm32/f1/gpio.c
+++ b/lib/stm32/f1/gpio.c
@@ -292,7 +292,7 @@ value cannot be ascertained from the hardware.
 */
 void gpio_primary_remap(u8 swjdisable, u32 maps)
 {
-	AFIO_MAPR = swjdisable | (maps & 0x1FFFFF);
+	AFIO_MAPR |= swjdisable | (maps & 0x1FFFFF);
 }
 
 /*-----------------------------------------------------------------------------*/
@@ -310,7 +310,7 @@ The AFIO remapping feature is used only with the STM32F10x series.
 */
 void gpio_secondary_remap(u32 maps)
 {
-	AFIO_MAPR2 = maps;
+	AFIO_MAPR2 |= maps;
 }
 
 /**@}*/