diff --git a/lib/libc/gdtoa/Makefile.inc b/lib/libc/gdtoa/Makefile.inc
index f66547e3e8d..6b240a0c1ca 100644
--- a/lib/libc/gdtoa/Makefile.inc
+++ b/lib/libc/gdtoa/Makefile.inc
@@ -4,7 +4,10 @@
 .PATH: ${.CURDIR}/gdtoa
 CPPFLAGS+=-I${.CURDIR}/gdtoa -I${.CURDIR}/locale
 
-.if ${MACHINE_ARCH} == "vax"
+# vax: no IEEE 754 compliant, and no fenv support at the moment.
+# mips: Honor_FLT_ROUNDS is broken for R3000; see port-mips/57680.
+.if ${MACHINE_ARCH} == "vax" || \
+    (${MACHINE_CPU} == "mips" && empty(MACHINE_ARCH:M*64*))
 CPPFLAGS+=-DNO_FENV_H
 .else
 CPPFLAGS+=-DHonor_FLT_ROUNDS