Make says "missing separator" for source .c file from CuTest

Make says "missing separator" for source .c file from CuTest

I'm trying to get started with CuTest to do unit testing in C.
When make-ing, I get the following error:
dev:~/bistro# make
cutest/CuTest.c:10: *** missing separator. Stop.
The file cutest/CuTest.c comes directly from the library. I have done no
mods to it. Here are the concerned lines:
08 - #include "CuTest.h"
09 -
10 -
/*-------------------------------------------------------------------------*
11 - * CuStr
12 -
*-------------------------------------------------------------------------*/
13 -
14 - char* CuStrAlloc(int size)



Here's the Makefile I'm using, for complete reference:
NAME = bistro
SOURCES_DIR = src
OBJECTS_DIR = obj
SOURCES = $(shell find $(SOURCES_DIR) -type f -name *.c) cutest/CuTest.c
OBJECTS = $(patsubst $(SOURCES_DIR)/%.c, $(OBJECTS_DIR)/%.o, $(SOURCES))
DEPS = $(OBJECTS:.o=.d)
CFLAGS = -Wall -Werror -Wextra
COMPILER = gcc -I cutest -I $(SOURCES_DIR) $(CFLAGS)
BISTRO_MAIN = $(OBJECTS_DIR)/bistro/bistro_main.o
.PHONY: test all clean fclean re
all: $(NAME)
# header dependencies
-include $(DEPS)
$(NAME): $(OBJECTS)
$(COMPILER) -o $(NAME) $(OBJECTS)
test: $(filter-out $(BISTRO_MAIN), $(OBJECTS))
$(COMPILER) -c all_tests.c -o all_tests.o
$(COMPILER) -o test $(filter-out $(BISTRO_MAIN), $(OBJECTS)) all_tests.o
rm -f all_tests.o
$(OBJECTS_DIR)/%.o: $(SOURCES_DIR)/%.c
@if [ ! -d "$(@D)" ]; then mkdir -p $(@D); fi
$(COMPILER) -MMD -c $< -o $@
clean:
rm -Rf $(OBJECTS_DIR)/*
fclean: clean
rm -f $(NAME)
re: fclean all
What could be the cause of this error message?