diff --git a/testhal/STM32F1xx/I2C/i2c_pns.c b/testhal/STM32F1xx/I2C/i2c_pns.c
index 8dbcbcb5c..7572b9edf 100644
--- a/testhal/STM32F1xx/I2C/i2c_pns.c
+++ b/testhal/STM32F1xx/I2C/i2c_pns.c
@@ -36,7 +36,7 @@
 static const I2CConfig i2cfg1 = {
     OPMODE_I2C,
     400000,
-    FAST_DUTY_CYCLE_16_9,
+    FAST_DUTY_CYCLE_2,
 };
 
 
diff --git a/testhal/STM32F4xx/I2C/main.c b/testhal/STM32F4xx/I2C/main.c
index 7edb8e8fd..8cfe10e8c 100644
--- a/testhal/STM32F4xx/I2C/main.c
+++ b/testhal/STM32F4xx/I2C/main.c
@@ -137,7 +137,7 @@ int main(void) {
   static const I2CConfig i2cfg2 = {
       OPMODE_I2C,
       400000,
-      FAST_DUTY_CYCLE_16_9,
+      FAST_DUTY_CYCLE_2,
   };
   i2cStart(&I2CD2, &i2cfg2);