diff --git a/bsp/stm32f10x/rtconfig.py b/bsp/stm32f10x/rtconfig.py
index 20a843ba4..4ebbb68aa 100644
--- a/bsp/stm32f10x/rtconfig.py
+++ b/bsp/stm32f10x/rtconfig.py
@@ -79,6 +79,7 @@ elif PLATFORM == 'armcc':
     AFLAGS = DEVICE
     LFLAGS = DEVICE + ' --info sizes --info totals --info unused --info veneers --list rtthread-stm32.map --scatter stm32_rom.sct'
 
+    CFLAGS += ' --c99'
     CFLAGS += ' -I' + EXEC_PATH + '/ARM/RV31/INC'
     LFLAGS += ' --libpath ' + EXEC_PATH + '/ARM/RV31/LIB'
 
diff --git a/bsp/stm32f10x/template.uvproj b/bsp/stm32f10x/template.uvproj
index 9304eff62..acb78f690 100644
--- a/bsp/stm32f10x/template.uvproj
+++ b/bsp/stm32f10x/template.uvproj
@@ -347,6 +347,7 @@
             <wLevel>0</wLevel>
             <uThumb>0</uThumb>
             <uSurpInc>0</uSurpInc>
+            <uC99>1</uC99>
             <VariousControls>
               <MiscControls></MiscControls>
               <Define></Define>
diff --git a/bsp/stm32f10x/template.uvprojx b/bsp/stm32f10x/template.uvprojx
index c6aff7241..0d439a6b7 100644
--- a/bsp/stm32f10x/template.uvprojx
+++ b/bsp/stm32f10x/template.uvprojx
@@ -350,6 +350,7 @@
             <wLevel>0</wLevel>
             <uThumb>0</uThumb>
             <uSurpInc>0</uSurpInc>
+            <uC99>1</uC99>
             <VariousControls>
               <MiscControls></MiscControls>
               <Define></Define>