diff --git a/math/coq/Makefile b/math/coq/Makefile
index 8e85c3b8dcf2..dd9757d6e5c1 100644
--- a/math/coq/Makefile
+++ b/math/coq/Makefile
@@ -1,65 +1,68 @@
 PORTNAME=	coq
 PORTVERSION=	8.6
 PORTREVISION=	10
 PORTEPOCH=	3
 CATEGORIES=	math
 MASTER_SITES=	http://coq.inria.fr/distrib/V${PORTVERSION}/files/ \
 		ftp://ftp.stack.nl/pub/users/johans/coq/
 PKGNAMESUFFIX=	${EMACS_PKGNAMESUFFIX}
 
 MAINTAINER=	hrs@FreeBSD.org
 COMMENT=	Theorem prover based on lambda-C
 
 LICENSE=	LGPL21
 LICENSE_FILE=	${WRKSRC}/LICENSE
 
 BROKEN_armv6=	fails to compile: Fatal error: exception Invalid_argument("index out of bounds")
 BROKEN_armv7=	fails to compile: Fatal error: exception Invalid_argument("index out of bounds")
 BROKEN_powerpc=	fails to link
 
 BUILD_DEPENDS=	camlp5:devel/ocaml-camlp5 \
 		ocamlfind:devel/ocaml-findlib
 LIB_DEPENDS=	libfontconfig.so:x11-fonts/fontconfig \
 		libfreetype.so:print/freetype2
 
 USES=		emacs gettext-runtime gmake gnome
 USE_GNOME=	atk cairo gdkpixbuf2 glib20 gtk20 gtksourceview2 pango
 USE_LDCONFIG=	${PREFIX}/lib/coq
 USE_OCAML=	yes
 
 HAS_CONFIGURE=	yes
 CONFIGURE_ARGS=	-prefix ${PREFIX} \
 		-mandir ${PREFIX}/man \
 		-emacslib ${PREFIX}/share/emacs/site-lisp/coq \
 		-usecamlp5 \
 		-byteonly
-MAKE_ENV=	VERBOSE=1
+MAKE_ENV=	VERBOSE=1 USERFLAGS=-unsafe-string
 ALL_TARGET=	world
 
 CONFLICTS_INSTALL=	coq coq-emacs_* # bin/coq-tex bin/coq_makefile bin/coqc bin/coqchk bin/coqdep bin/coqdoc bin/coqide bin/coqmktop bin/coqtop bin/coqtop.byte bin/coqwc bin/coqworkmgr bin/gallina
 
 OPTIONS_DEFINE=		DOCS IDE
 OPTIONS_DEFAULT=	IDE
 OPTIONS_SUB=		yes
 IDE_DESC=		Include desktop environment (coqide)
 IDE_BUILD_DEPENDS=	lablgtk2:x11-toolkits/ocaml-lablgtk2
 IDE_RUN_DEPENDS=	lablgtk2:x11-toolkits/ocaml-lablgtk2
 IDE_CONFIGURE_OFF=	-coqide no
 DOCS_USE=		TEX=latex:build,dvipsk:build,texmf:build
 DOCS_BUILD_DEPENDS=	hevea:textproc/hevea
 DOCS_CONFIGURE_OFF=	-with-doc no
 
 STRIP_FILES=		lib/coq/dllcoqrun.so
 
 # Workaround bsd.ocaml.mk to fix packaging
 add-plist-post:
 	@${DO_NADA}
 
 post-patch:
-	${REINPLACE_CMD} -e '/show_latex_mes/s/)$$/; true)/' \
-	    ${WRKSRC}/Makefile.doc
+	@${REINPLACE_CMD} -e '/show_latex_mes/s/)$$/; true)/' \
+		${WRKSRC}/Makefile.doc
+# Allow passing USERFLAGS down to inner make(1) via environment
+	@${REINPLACE_CMD} -e '/User compilation flag/,+1d' \
+		${WRKSRC}/configure.ml
 
 post-install:
 	cd ${STAGEDIR}${PREFIX} && ${STRIP_CMD} ${STRIP_FILES}
 
 .include <bsd.port.mk>
diff --git a/math/coq/files/patch-Makefile.build b/math/coq/files/patch-Makefile.build
index b66ed54c2c10..15fa789877ed 100644
--- a/math/coq/files/patch-Makefile.build
+++ b/math/coq/files/patch-Makefile.build
@@ -1,11 +1,29 @@
 --- Makefile.build.orig	2016-12-08 15:13:52 UTC
 +++ Makefile.build
-@@ -101,7 +101,7 @@ TIMER=$(if $(TIMED), $(STDTIME), $(TIMEC
+@@ -101,7 +101,7 @@ TIMER=$(if $(TIMED), $(STDTIME), $(TIMECMD))
  #   TIME="%C (%U user, %S sys, %e total, %M maxres)"
  
  COQOPTS=$(COQ_XML) $(NATIVECOMPUTE)
 -BOOTCOQC=$(TIMER) $(COQTOPEXE) -boot $(COQOPTS) -compile
 +BOOTCOQC=$(TIMER) env CAML_LD_LIBRARY_PATH=$${PWD}/kernel/byterun $(COQTOPEXE) -boot $(COQOPTS) -compile
  
  LOCALINCLUDES=$(addprefix -I , $(SRCDIRS) )
  MLINCLUDES=$(LOCALINCLUDES) -I $(MYCAMLP4LIB)
+@@ -334,7 +334,7 @@ coqbinaries: $(COQMKTOP) $(COQTOPEXE) $(COQTOPBYTE) \
+ ifeq ($(BEST),opt)
+ $(COQTOPEXE): $(COQMKTOP) $(LINKCMX) $(LIBCOQRUN) $(TOPLOOPCMA:.cma=.cmxs)
+ 	$(SHOW)'COQMKTOP -o $@'	
+-	$(HIDE)$(COQMKTOP) -boot -opt $(OPTFLAGS) $(LINKMETADATA) -o $@
++	$(HIDE)$(COQMKTOP) -boot -opt $(filter-out -unsafe-string, $(OPTFLAGS)) $(LINKMETADATA) -o $@
+ 	$(STRIP) $@
+ 	$(CODESIGN) $@
+ else
+@@ -344,7 +344,7 @@ endif
+ 
+ $(COQTOPBYTE): $(COQMKTOP) $(LINKCMO) $(LIBCOQRUN) $(TOPLOOPCMA)
+ 	$(SHOW)'COQMKTOP -o $@'	
+-	$(HIDE)$(COQMKTOP) -boot -top $(BYTEFLAGS) -o $@
++	$(HIDE)$(COQMKTOP) -boot -top $(filter-out -unsafe-string, $(BYTEFLAGS)) -o $@
+ 
+ # coqmktop
+