Assembler error (2.4.0t9 gcc-2.97)

[nbecker@fred.net]

linux-2.4.0-test9
gcc-2.97 CVS
configured for Athlon
binutils-2.9.5.0.22-6

Do I need an updated binutils maybe?
 as --version
GNU assembler 2.9.5

[...]
gcc -D__KERNEL__ -I/usr/src/linux-2.4.0-test9/include -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer -pipe  -mpreferred-stack-boundary=2 -march=athlon  -fno-strict-aliasing    -c -o mmx.o mmx.c
{standard input}: Assembler messages:
{standard input}:151: Error: bad register name `%%mm0'
make[2]: *** [mmx.o] Error 1