diff --git a/bsp/lm4f232/rtconfig.py b/bsp/lm4f232/rtconfig.py
index b34cab7f8..cfe518891 100644
--- a/bsp/lm4f232/rtconfig.py
+++ b/bsp/lm4f232/rtconfig.py
@@ -44,7 +44,7 @@ if PLATFORM == 'gcc':
 
     DEVICE = ' -mcpu=cortex-m4 -mthumb -mfpu=fpv4-sp-d16 -mfloat-abi=softfp -ffunction-sections -fdata-sections'
     CFLAGS = DEVICE 
-    AFLAGS = ' -c' + DEVICE + ' -x assembler-with-cpp -Wa,-mimplicit-it=thumb,'
+    AFLAGS = ' -c' + DEVICE + ' -x assembler-with-cpp -Wa,-mimplicit-it=thumb '
     LFLAGS = DEVICE + ' -Wl,--gc-sections,-Map=rtthread-lm4f.map,-cref,-u,Reset_Handler -T lm4f_rom.ld'
 
     CPATH = ''
diff --git a/bsp/stm32f40x/rtconfig.py b/bsp/stm32f40x/rtconfig.py
index 97ffb66f4..8621d6a09 100644
--- a/bsp/stm32f40x/rtconfig.py
+++ b/bsp/stm32f40x/rtconfig.py
@@ -42,7 +42,7 @@ if PLATFORM == 'gcc':
 
     DEVICE = ' -mcpu=cortex-m4 -mthumb -mfpu=fpv4-sp-d16 -mfloat-abi=softfp -ffunction-sections -fdata-sections'
     CFLAGS = DEVICE 
-    AFLAGS = ' -c' + DEVICE + ' -x assembler-with-cpp -Wa,-mimplicit-it=thumb,'
+    AFLAGS = ' -c' + DEVICE + ' -x assembler-with-cpp -Wa,-mimplicit-it=thumb '
     LFLAGS = DEVICE + ' -Wl,--gc-sections,-Map=rtthread-stm32.map,-cref,-u,Reset_Handler -T stm32_rom.ld'
 
     CPATH = ''
diff --git a/bsp/xplorer4330/m4/rtconfig.py b/bsp/xplorer4330/m4/rtconfig.py
index a691578c9..0b61eda45 100644
--- a/bsp/xplorer4330/m4/rtconfig.py
+++ b/bsp/xplorer4330/m4/rtconfig.py
@@ -48,7 +48,7 @@ if PLATFORM == 'gcc':
 
     DEVICE = ' -mcpu=cortex-m4 -mthumb -mfpu=fpv4-sp-d16 -mfloat-abi=softfp -ffunction-sections -fdata-sections'
     CFLAGS = DEVICE 
-    AFLAGS = ' -c' + DEVICE + ' -x assembler-with-cpp -Wa,-mimplicit-it=thumb,'
+    AFLAGS = ' -c' + DEVICE + ' -x assembler-with-cpp -Wa,-mimplicit-it=thumb '
     LFLAGS = DEVICE + ' -Wl,--gc-sections,-Map=rtthread-lpc4330.map,-cref,-u,Reset_Handler -T lpc4330_xplorer_spifi32mb.ld'
 
     CPATH = ''