diff --git a/demos/nil/NIL-STM32F100-DISCOVERY/Makefile b/demos/nil/NIL-STM32F100-DISCOVERY/Makefile
index 9c3e19098..562fc1dfe 100644
--- a/demos/nil/NIL-STM32F100-DISCOVERY/Makefile
+++ b/demos/nil/NIL-STM32F100-DISCOVERY/Makefile
@@ -137,7 +137,7 @@ INCDIR = $(PORTINC) $(KERNINC) $(TESTINC) \
 # Compiler settings
 #
 
-MCU  = cortex-m4
+MCU  = cortex-m3
 
 #TRGT = arm-elf-
 TRGT = arm-none-eabi-
diff --git a/demos/rt/RT-STM32F100-DISCOVERY/Makefile b/demos/rt/RT-STM32F100-DISCOVERY/Makefile
index f20ddb669..08d7ef178 100644
--- a/demos/rt/RT-STM32F100-DISCOVERY/Makefile
+++ b/demos/rt/RT-STM32F100-DISCOVERY/Makefile
@@ -137,7 +137,7 @@ INCDIR = $(PORTINC) $(KERNINC) $(TESTINC) \
 # Compiler settings
 #
 
-MCU  = cortex-m4
+MCU  = cortex-m3
 
 #TRGT = arm-elf-
 TRGT = arm-none-eabi-
diff --git a/demos/rt/RT-STM32F103-OLIMEX_STM32_P103/Makefile b/demos/rt/RT-STM32F103-OLIMEX_STM32_P103/Makefile
index 9b705c776..851ea0b4b 100644
--- a/demos/rt/RT-STM32F103-OLIMEX_STM32_P103/Makefile
+++ b/demos/rt/RT-STM32F103-OLIMEX_STM32_P103/Makefile
@@ -137,7 +137,7 @@ INCDIR = $(PORTINC) $(KERNINC) $(TESTINC) \
 # Compiler settings
 #
 
-MCU  = cortex-m4
+MCU  = cortex-m3
 
 #TRGT = arm-elf-
 TRGT = arm-none-eabi-
diff --git a/testhal/STM32F1xx/ADC/Makefile b/testhal/STM32F1xx/ADC/Makefile
index edae9130e..262550b9f 100644
--- a/testhal/STM32F1xx/ADC/Makefile
+++ b/testhal/STM32F1xx/ADC/Makefile
@@ -137,7 +137,7 @@ INCDIR = $(PORTINC) $(KERNINC) $(TESTINC) \
 # Compiler settings
 #
 
-MCU  = cortex-m4
+MCU  = cortex-m3
 
 #TRGT = arm-elf-
 TRGT = arm-none-eabi-
diff --git a/testhal/STM32F1xx/CAN/Makefile b/testhal/STM32F1xx/CAN/Makefile
index edae9130e..262550b9f 100644
--- a/testhal/STM32F1xx/CAN/Makefile
+++ b/testhal/STM32F1xx/CAN/Makefile
@@ -137,7 +137,7 @@ INCDIR = $(PORTINC) $(KERNINC) $(TESTINC) \
 # Compiler settings
 #
 
-MCU  = cortex-m4
+MCU  = cortex-m3
 
 #TRGT = arm-elf-
 TRGT = arm-none-eabi-
diff --git a/testhal/STM32F1xx/EXT/Makefile b/testhal/STM32F1xx/EXT/Makefile
index edae9130e..262550b9f 100644
--- a/testhal/STM32F1xx/EXT/Makefile
+++ b/testhal/STM32F1xx/EXT/Makefile
@@ -137,7 +137,7 @@ INCDIR = $(PORTINC) $(KERNINC) $(TESTINC) \
 # Compiler settings
 #
 
-MCU  = cortex-m4
+MCU  = cortex-m3
 
 #TRGT = arm-elf-
 TRGT = arm-none-eabi-
diff --git a/testhal/STM32F1xx/IRQ_STORM/Makefile b/testhal/STM32F1xx/IRQ_STORM/Makefile
index edae9130e..262550b9f 100644
--- a/testhal/STM32F1xx/IRQ_STORM/Makefile
+++ b/testhal/STM32F1xx/IRQ_STORM/Makefile
@@ -137,7 +137,7 @@ INCDIR = $(PORTINC) $(KERNINC) $(TESTINC) \
 # Compiler settings
 #
 
-MCU  = cortex-m4
+MCU  = cortex-m3
 
 #TRGT = arm-elf-
 TRGT = arm-none-eabi-
diff --git a/testhal/STM32F1xx/PWM-ICU/Makefile b/testhal/STM32F1xx/PWM-ICU/Makefile
index edae9130e..262550b9f 100644
--- a/testhal/STM32F1xx/PWM-ICU/Makefile
+++ b/testhal/STM32F1xx/PWM-ICU/Makefile
@@ -137,7 +137,7 @@ INCDIR = $(PORTINC) $(KERNINC) $(TESTINC) \
 # Compiler settings
 #
 
-MCU  = cortex-m4
+MCU  = cortex-m3
 
 #TRGT = arm-elf-
 TRGT = arm-none-eabi-
diff --git a/testhal/STM32F1xx/SPI/Makefile b/testhal/STM32F1xx/SPI/Makefile
index edae9130e..262550b9f 100644
--- a/testhal/STM32F1xx/SPI/Makefile
+++ b/testhal/STM32F1xx/SPI/Makefile
@@ -137,7 +137,7 @@ INCDIR = $(PORTINC) $(KERNINC) $(TESTINC) \
 # Compiler settings
 #
 
-MCU  = cortex-m4
+MCU  = cortex-m3
 
 #TRGT = arm-elf-
 TRGT = arm-none-eabi-
diff --git a/testhal/STM32F1xx/UART/Makefile b/testhal/STM32F1xx/UART/Makefile
index edae9130e..262550b9f 100644
--- a/testhal/STM32F1xx/UART/Makefile
+++ b/testhal/STM32F1xx/UART/Makefile
@@ -137,7 +137,7 @@ INCDIR = $(PORTINC) $(KERNINC) $(TESTINC) \
 # Compiler settings
 #
 
-MCU  = cortex-m4
+MCU  = cortex-m3
 
 #TRGT = arm-elf-
 TRGT = arm-none-eabi-
diff --git a/testhal/STM32F1xx/USB_CDC/Makefile b/testhal/STM32F1xx/USB_CDC/Makefile
index 2e748969a..6757f3a6e 100644
--- a/testhal/STM32F1xx/USB_CDC/Makefile
+++ b/testhal/STM32F1xx/USB_CDC/Makefile
@@ -139,7 +139,7 @@ INCDIR = $(PORTINC) $(KERNINC) $(TESTINC) \
 # Compiler settings
 #
 
-MCU  = cortex-m4
+MCU  = cortex-m3
 
 #TRGT = arm-elf-
 TRGT = arm-none-eabi-