1 files changed, 3 insertions, 3 deletions
diff --git a/os/hal/platforms/STM32/ext_lld.c b/os/hal/platforms/STM32/ext_lld.c
index 4a3cd3c2e..ed80f524c 100644
--- a/os/hal/platforms/STM32/ext_lld.c
+++ b/os/hal/platforms/STM32/ext_lld.c
@@ -577,11 +577,11 @@ void ext_lld_channel_enable(EXTDriver *extp, expchannel_t channel) {
 
   /* Setting the associated GPIO for external channels.*/
   if (channel < 16) {
-    uint32_t n = channel & 3;
-    uint32_t mask = 0xF << (channel >> 2);
+    uint32_t n = channel >> 2;
+    uint32_t mask = ~(0xF << (channel & 3));
     uint32_t port = ((extp->config->channels[channel].mode &
                       EXT_MODE_GPIO_MASK) >>
-                     EXT_MODE_GPIO_OFF) << (channel >> 2);
+                     EXT_MODE_GPIO_OFF) << (channel & 3);
 
 #if defined(STM32L1XX_MD) || defined(STM32F2XX) || defined(STM32F4XX)
   SYSCFG->EXTICR[n] = (SYSCFG->EXTICR[n] & mask) | port;