diff --git a/examples/module/rtconfig_lm3s.py b/examples/module/rtconfig_lm3s.py
index 7958047f2b..0f81c67a48 100644
--- a/examples/module/rtconfig_lm3s.py
+++ b/examples/module/rtconfig_lm3s.py
@@ -15,7 +15,7 @@ OBJDUMP = PREFIX + 'objdump'
 OBJCPY = PREFIX + 'objcopy'
 
 DEVICE = ' -mcpu=cortex-m3'
-CFLAGS = DEVICE + ' -mthumb -Dsourcerygxx -O0 -fPIC'
+CFLAGS = DEVICE + ' -mthumb -mlong-calls -Dsourcerygxx -O0 -fPIC'
 AFLAGS = ' -c' + DEVICE + ' -x assembler-with-cpp'
 LFLAGS = DEVICE + ' -mthumb -Wl,-z,max-page-size=0x4 -shared -fPIC -e main -nostdlib'