diff --git a/avr-gcc-toolchain.cmake b/avr-gcc-toolchain.cmake
index 6c0a425..186e108 100644
--- a/avr-gcc-toolchain.cmake
+++ b/avr-gcc-toolchain.cmake
@@ -15,9 +15,10 @@ set(AVR_MCU attiny13a)
 #set(AVR_MCU avr64dd28) # Newer DX series, avrxmega2
 
 #set(F_CPU 16000000UL)
-#set(F_CPU 8000000)
-set(F_CPU 9600000)
-#set(F_CPU 4800000)
+#set(F_CPU 8000000UL)
+#set(F_CPU 9600000UL)
+set(F_CPU 1200000UL)
+#set(F_CPU 4800000UL)
 
 add_compile_definitions(F_CPU=${F_CPU})
 # add_compile_definitions(MCU=atmega328p)