diff --git a/Makefile.include b/Makefile.include
index 73154fbc5..916d07df9 100644
--- a/Makefile.include
+++ b/Makefile.include
@@ -42,7 +42,7 @@ endif
 
 LOWERCASE = -abcdefghijklmnopqrstuvwxyz
 UPPERCASE = _ABCDEFGHIJKLMNOPQRSTUVWXYZ
-TARGET_UPPERCASE := ${shell echo $(TARGET) | sed 'y!$(LOWERCASE)!$(UPPERCASE)!'}
+TARGET_UPPERCASE := ${strip ${shell echo $(TARGET) | sed y!$(LOWERCASE)!$(UPPERCASE)!}}
 CFLAGS += -DCONTIKI=1 -DCONTIKI_TARGET_$(TARGET_UPPERCASE)=1
 
 include $(CONTIKI)/core/net/rime/Makefile.rime