The ATmega328 and ATmega328P have different signatures.
ATmega328: 1E 95 14
ATmega328P: 1E 95 0F
Most of the entries in BOARDS.TXT for boards with 328 processor specify the 328P. You may need to create a custom board definition. You can create a local "boards.txt" file in a directory inside a directory called "hardware" in the folder that contains your sketches. You have to re-start the Arduino program to get it to recognize the new boards.