diff --git a/Arduino.mk b/Arduino.mk
index ff395d0..2448c03 100644
--- a/Arduino.mk
+++ b/Arduino.mk
@@ -702,7 +702,7 @@ endif
 ifeq ($(strip $(NO_CORE)),)
     ifndef MONITOR_BAUDRATE
         ifeq ($(words $(LOCAL_PDE_SRCS) $(LOCAL_INO_SRCS)), 1)
-            SPEED = $(shell egrep -h 'Serial.begin\([0-9]+\)' $(LOCAL_PDE_SRCS) $(LOCAL_INO_SRCS) | sed -e 's/[^0-9]//g'| head -n1)
+            SPEED = $(shell egrep -h 'Serial.begin *\([0-9]+\)' $(LOCAL_PDE_SRCS) $(LOCAL_INO_SRCS) | sed -e 's/[^0-9]//g'| head -n1)
             MONITOR_BAUDRATE = $(findstring $(SPEED),300 1200 2400 4800 9600 14400 19200 28800 38400 57600 115200)
         endif