diff --git a/examples/stm32f2/Makefile.include b/examples/stm32f2/Makefile.include
index 6ec9f65b..9cec6e7d 100644
--- a/examples/stm32f2/Makefile.include
+++ b/examples/stm32f2/Makefile.include
@@ -20,7 +20,7 @@
 ##
 
 PREFIX	?= arm-none-eabi
-#PREFIX		?= arm-elf
+# PREFIX		?= arm-elf
 CC		= $(PREFIX)-gcc
 LD		= $(PREFIX)-gcc
 OBJCOPY		= $(PREFIX)-objcopy
diff --git a/lib/lm3s/Makefile b/lib/lm3s/Makefile
index 2bdbd720..e2be89fa 100644
--- a/lib/lm3s/Makefile
+++ b/lib/lm3s/Makefile
@@ -19,8 +19,8 @@
 
 LIBNAME		= libopencm3_lm3s
 
-# PREFIX	?= arm-none-eabi
-PREFIX		?= arm-elf
+PREFIX	?= arm-none-eabi
+# PREFIX		?= arm-elf
 CC		= $(PREFIX)-gcc
 AR		= $(PREFIX)-ar
 CFLAGS		= -Os -g -Wall -Wextra -I../../include -fno-common \
diff --git a/lib/lpc13xx/Makefile b/lib/lpc13xx/Makefile
index 7181a08b..9b903167 100644
--- a/lib/lpc13xx/Makefile
+++ b/lib/lpc13xx/Makefile
@@ -19,8 +19,8 @@
 
 LIBNAME		= libopencm3_lpc13xx
 
-# PREFIX	?= arm-none-eabi
-PREFIX		?= arm-elf
+PREFIX	?= arm-none-eabi
+# PREFIX		?= arm-elf
 CC		= $(PREFIX)-gcc
 AR		= $(PREFIX)-ar
 CFLAGS		= -Os -g -Wall -Wextra -I../../include -fno-common \
diff --git a/lib/stm32f1/Makefile b/lib/stm32f1/Makefile
index a6aed450..f2f53827 100644
--- a/lib/stm32f1/Makefile
+++ b/lib/stm32f1/Makefile
@@ -19,8 +19,8 @@
 
 LIBNAME		= libopencm3_stm32f1
 
-# PREFIX	?= arm-none-eabi
-PREFIX		?= arm-elf
+PREFIX	?= arm-none-eabi
+# PREFIX		?= arm-elf
 CC		= $(PREFIX)-gcc
 AR		= $(PREFIX)-ar
 CFLAGS		= -Os -g -Wall -Wextra -I../../include -fno-common \
diff --git a/lib/stm32f2/Makefile b/lib/stm32f2/Makefile
index cd50c4b8..5da64ab3 100644
--- a/lib/stm32f2/Makefile
+++ b/lib/stm32f2/Makefile
@@ -19,8 +19,8 @@
 
 LIBNAME		= libopencm3_stm32f2
 
-# PREFIX	?= arm-none-eabi
-PREFIX		?= arm-elf
+PREFIX	?= arm-none-eabi
+# PREFIX		?= arm-elf
 CC		= $(PREFIX)-gcc
 AR		= $(PREFIX)-ar
 CFLAGS		= -Os -g -Wall -Wextra -I../../include -fno-common \
@@ -28,7 +28,7 @@ CFLAGS		= -Os -g -Wall -Wextra -I../../include -fno-common \
 		  -ffunction-sections -fdata-sections -MD -DSTM32F2
 # ARFLAGS	= rcsv
 ARFLAGS		= rcs
-OBJS		= vector.o gpio.o systick.o i2c.o spi.o nvic.o
+OBJS		= vector.o gpio.o systick.o i2c.o spi.o nvic.o usart.o
 
 #VPATH += ../usb
 VPATH += ../stm32_common