diff --git a/arch/arm/include/stm32l4/chip.h b/arch/arm/include/stm32l4/chip.h
index d9311b0909..07139d18b9 100644
--- a/arch/arm/include/stm32l4/chip.h
+++ b/arch/arm/include/stm32l4/chip.h
@@ -285,7 +285,7 @@
 #  define STM32L4_NLPTIM                   2   /* Two low-power timers, LPTIM1-2 */
 #  define STM32L4_NRNG                     1   /* Random number generator (RNG) */
 #  define STM32L4_NUART                    0   /* No UART */
-#  define STM32L4_NUSART                   4   /* USART 1-4 */
+#  define STM32L4_NUSART                   3   /* USART 1-3 */
 #  define STM32L4_NLPUART                  1   /* LPUART 1 */
 #  define STM32L4_QSPI                     1   /* QuadSPI1 */
 #  define STM32L4_NSPI                     3   /* SPI1-SPI3 */