# XXX Causes a segfault during the bootstrapping
-CFLAGS="${CFLAGS/-ftree-loop-if-convert-stores}" &&
+CFLAGS="${CFLAGS//-ftree-loop-if-convert-stores}" &&
+# XXX Emacs 27.1 fails to build if restricted to finite math
+CFLAGS="${CFLAGS//-ffast-math}" &&