diff --git a/fetch_impls.sh b/fetch_impls.sh
index 4a4a184..f760ffc 100755
--- a/fetch_impls.sh
+++ b/fetch_impls.sh
@@ -77,7 +77,7 @@ for impl in ../sysdeps/x86_64/multiarch/memmove-*.S; do
     -DSHARED \
     -DTOP_NAMESPACE=glibc \
     -DASSEMBLER \
-    -DISA_DEFAULT_IMPL \
+    -march=core2 \
     -g \
     -S \
     > "${workdir}/impls/${impl_basename%.S}.s"