WINAVR not finding file in include path with white

When I supply an path for EXTRAINCDIRS (in the Makefile, following the sample provided by WINAVR) without whitespace, the compiler is able to find my header file, but when I use a path containing whitespace (enclosed in quotation marks, as the comments in the Makefile direct), it raises: error: No such file or directory.

"d:/dev/avr/atmega/shared/" # will search files in this dir
"d:/dev/avr/atmega/sha ed/" # will not search this dir for files

I mean, the comments say:

# List any extra directories to look for include files here.
#     Each directory must be seperated by a space.
#     Use forward slashes for directory separators.
#     For a directory that has spaces, enclose it in quotes.

Any idea how to get WINAVR to handle this correctly?

I'm using Programmer's Notepad (WINAVR) on Windows XP. Here's the command line command:

avr-g++ -c -mmcu=atmega328p -I. -gdwarf-2 -DF_CPU=UL -Os -funsigned-char -funsigned-bitfields -fpack-struct -fshort-enums -Wall -Wstrict-prototypes -Wa,-adhlns=./main.lst -I"d:/dev/avr/atmega/shared/" -I"d:/dev/avr/atmega/sha -Ied/" -std=gnu99 -MMD -MP -MF .dep/main.o.d main.c -o main.o

What is happening is that I'm guessing somewhere else in the makefile there is a line that does something like the following:

INCLUDES = $(addprefix -I, $(INCDIRS))

When that happens addprefix treats any spaces in the $(INCDIRS) variable as a seperator to the next variable and will add the -I there. What you could do is use a special character for spaces say '\\' and then before the command is generated call a substitute function to resubstitute spaces. Something like the below example:

SPACE = \\
INCDIRS = /home/posey/test$(SPACE)dir

INCLUDES = $(addprefix -I, $(INCDIRS))
REAL_INCLUDES = $(subst $(SPACE), ,$(INCLUDES))

.PHONY : all

all:
    $(info $(REAL_INCLUDES))

If this doesn't make sense you can post the entire makefile and we can show you exactly what's going on. Once the space has been substituted back into the variable you cannot run it through any further make functions that work with space delimiters without the same behavior occurring.