Why Makefile is compiling a file type FILE while should be a .exe?

Basically the title. The makefile looks like this:

all: lab03

lab03: lab03.o represa.o
    gcc lab03.o represa.o -lm -o lab03

lab03.o: lab03.c represa.h
    gcc -std=c99 -Wall -Werror -Werror=vla -g -c lab03.c

represa.o: represa.c represa.h
    gcc -std=c99 -Wall -Werror -Werror=vla -g -c represa.c

clean:
    rm *.o lab03

I use the makefile in wsl, if that changes anything.