diff --git a/avr-gcc-toolchain.cmake b/avr-gcc-toolchain.cmake
index 27ac326..dd574a5 100644
--- a/avr-gcc-toolchain.cmake
+++ b/avr-gcc-toolchain.cmake
@@ -2,7 +2,7 @@
 set(CMAKE_SYSTEM_NAME Generic)
 set(CMAKE_SYSTEM_PROCESSOR avr)
 
-set(AVR_MCU "ATtiny24")
+set(AVR_MCU "attiny24")
 set(AVR_PROGRAMMER "usbasp")
 
 # compiler and linker settings