diff --git a/include/libopencm3/stm32/usart.h b/include/libopencm3/stm32/usart.h
index d98b9c26..2c29a832 100644
--- a/include/libopencm3/stm32/usart.h
+++ b/include/libopencm3/stm32/usart.h
@@ -34,6 +34,8 @@
 #       include <libopencm3/stm32/l0/usart.h>
 #elif defined(STM32L1)
 #       include <libopencm3/stm32/l1/usart.h>
+#elif defined(STM32L4)
+#       include <libopencm3/stm32/l4/usart.h>
 #else
 #       error "stm32 family not defined."
 #endif
diff --git a/lib/stm32/l4/Makefile b/lib/stm32/l4/Makefile
index 4c63b1cb..3b643cd7 100644
--- a/lib/stm32/l4/Makefile
+++ b/lib/stm32/l4/Makefile
@@ -47,6 +47,7 @@ OBJS            += adc_common_v2.o adc_common_v2_multi.o
 OBJS            += rng_common_v1.o
 OBJS            += timer_common_all.o
 OBJS            += i2c_common_v2.o
+OBJS            += usart_common_all.o usart_common_v2.o
 
 VPATH += ../../usb:../:../../cm3:../common
 VPATH += ../../ethernet