I am wondering how to correctly compile a program with a Makefile that has calls to yyparse in it? This is what I do: I have a Makefile that compiles all my regular files and they have no connections to y.tab.c or lex.yy.c (Am I supposed to have them?) I do this on top of my code: #include "y.tab.c" #include "lex.yy.c" #include "y.tab.h" This is what happens when I try to make the program: When I just type in "make", it gives me many warnings. Some of the examples are shown below. In function yywrap': /src/parser.y:12: multiple definition ofyywrap' server.o :/src/parser.y:12: first defined here utils.o: In function yyparse': /src/y.tab.c:1175: multiple definition ofyyparse' server.o:/src/y.tab.c:1175: first defined here utils.o I get many different errors referring to different yy_* files. I have compiled successfully with multiple calls to yyparse in the past, but this time seems to be different. It seems an awful lot like an inclusion problem somewhere but I can't tell what it is. All my header files have ifndef conditions, as well. Thanks for your help!