diff --git a/Makefile b/Makefile
--- a/Makefile
+++ b/Makefile
@@ -39,6 +39,7 @@ SRC+=stm32l1xx_it.c
 SRC+=system_stm32l1xx.c
 SRC+=stm32l100c_discovery.c
 SRC+=ssd1306.c
+SRC+=stringhelpers.c
 
 # Discovery Source Files
 #SRC+=stm32f4_discovery_lis302dl.c