diff --git a/dev-ml/lablgtk/files/lablgtk-2.18.10-cflags.patch b/dev-ml/lablgtk/files/lablgtk-2.18.10-cflags.patch
new file mode 100644
index 0000000000000..9cbc94a8a036d
--- /dev/null
+++ b/dev-ml/lablgtk/files/lablgtk-2.18.10-cflags.patch
@@ -0,0 +1,97 @@
+--- a/src/Makefile	2020-05-14 22:01:09.565870733 +0200
++++ b/src/Makefile	2020-05-14 22:06:49.081621996 +0200
+@@ -18,6 +18,7 @@
+ 
+ include $(CONFIG)
+ #GTKCFLAGS += -Werror -Wno-error=deprecated-declarations
++CFLAGS=
+ 
+ TARGETS = varcc$(XE) lablgtktop$(XE) lablgtk2$(XB) gdk_pixbuf_mlsource$(XE) \
+ 	$(THINITOBJS) build.ml
+@@ -45,14 +46,13 @@
+ 
+ ifdef DEBUG
+ COMPILER += -warn-error A-52
+-CFLAGS = -g $(GTKCFLAGS)
++OCAMLCFLAGS = $(GTKCFLAGS)
+ CUSTOM = -custom
+ #MLLINK += -cclib -lcamlrund
+ MLBYTEFLAGS = -g -dtypes
+ else
+-CFLAGS = -DG_DISABLE_ASSERT -DG_DISABLE_CAST_CHECKS $(GTKCFLAGS)
++OCAMLCFLAGS = -DG_DISABLE_ASSERT -DG_DISABLE_CAST_CHECKS $(GTKCFLAGS)
+ ifneq ($(TOOLCHAIN),msvc)
+-CFLAGS += -O
+ endif
+ endif
+ 
+@@ -65,9 +65,9 @@
+ THLINK = unix.cma threads.cma
+ 
+ ifdef USE_CC
+-CCOMPILER = $(CC) -c -I"$(LIBDIR)" $(CFLAGS)
++CCOMPILER = $(CC) -c -I"$(LIBDIR)" $(OCAMLCFLAGS) $(CFLAGS)
+ else
+-CCOMPILER = $(CAMLC) -c -ccopt '$(CFLAGS)' -verbose
++CCOMPILER = $(CAMLC) -c -ccopt '$(OCAMLCFLAGS) $(CFLAGS)' -verbose
+ endif
+ 
+ ifdef USE_GL
+@@ -123,7 +123,7 @@
+ CLIBS += liblablrsvg$(XA)
+ RSVGMLOBJS = rsvg.cmo
+ RSVGCOBJS = ml_rsvg$(XO)
+-$(RSVGCOBJS) : CFLAGS+=$(HAVE_SVGZ)
++$(RSVGCOBJS) : OCAMLCFLAGS+=$(HAVE_SVGZ)
+ endif
+ 
+ ifdef USE_GTKSPELL
+@@ -140,7 +140,7 @@
+ opt::  lablgtksourceview.cmxs
+ endif
+ 
+-ml_gtksourceview.o: CFLAGS=$(GTKSOURCEVIEWCFLAGS)
++ml_gtksourceview.o: OCAMLCFLAGS=$(GTKSOURCEVIEWCFLAGS)
+ GTKSOURCEVIEWMLOBJS = gtkSourceView.cmo gSourceView.cmo
+ GTKSOURCEVIEWCOBJS = ml_gtksourceview$(XO)
+ ml_gtksourceview.c: pango_tags.h
+@@ -179,7 +179,7 @@
+ endif
+ 
+ ifdef USE_GTKQUARTZ
+-CFLAGS += -DHAS_GTKQUARTZ
++OCAMLCFLAGS += -DHAS_GTKQUARTZ
+ endif
+ # Rules
+ .SUFFIXES: .ml .mli .cmo .cmi .cmx .cmxs .cmxa .c $(XO) .d$(XO) .var .h .opt .def .ml4
+@@ -188,7 +188,7 @@
+ .cpp$(XO):
+ 	$(CCOMPILER) $<
+ .c.d$(XO):
+-	$(CAMLC) -c -ccopt '-MT -DCAML_DLL -Fo$@ $(CFLAGS)' $<
++	$(CAMLC) -c -ccopt '-MT -DCAML_DLL -Fo$@ $(OCAMLCFLAGS) $(CFLAGS)' $<
+ .ml.cmo:
+ 	$(COMPILER) $(PRINCIPAL) $<
+ .mli.cmi:
+--- a/src/ml_gdk.h	2020-05-14 22:19:59.045394874 +0200
++++ b/src/ml_gdk.h	2020-05-14 22:20:06.694277819 +0200
+@@ -102,7 +102,7 @@
+ CAMLexport int OptFlags_GdkModifier_val (value);
+ CAMLexport int Flags_GdkModifier_val (value);
+ CAMLexport int Flags_Event_mask_val (value);
+-CAMLexport lookup_info *ml_table_extension_events;
++extern lookup_info *ml_table_extension_events;
+ #define Extension_events_val(key) ml_lookup_to_c(ml_table_extension_events,key)
+ 
+ #define GdkDragContext_val(val) check_cast(GDK_DRAG_CONTEXT,val)
+--- a/src/ml_gdk.c	2020-05-14 22:21:39.244861128 +0200
++++ b/src/ml_gdk.c	2020-05-14 22:21:57.571580518 +0200
+@@ -55,6 +55,8 @@
+ #define GDK_WINDOW_TYPE_HINT_DOCK GDK_WINDOW_TYPE_HINT_NORMAL
+ #endif
+ 
++lookup_info *ml_table_extension_events;
++
+ CAMLprim void ml_raise_gdk (const char *errmsg)
+ {
+   static const value * exn = NULL;
diff --git a/dev-ml/lablgtk/lablgtk-2.18.10.ebuild b/dev-ml/lablgtk/lablgtk-2.18.10.ebuild
index ad3698d27a55e..780d515a5e01b 100644
--- a/dev-ml/lablgtk/lablgtk-2.18.10.ebuild
+++ b/dev-ml/lablgtk/lablgtk-2.18.10.ebuild
@@ -26,6 +26,10 @@ BDEPEND="dev-ml/findlib
 
 DOCS=( CHANGES README CHANGES.API )
 
+PATCHES=(
+	"${FILESDIR}"/${P}-cflags.patch
+)
+
 src_configure() {
 	local myeconfargs=(
 		$(use_enable debug)
@@ -46,9 +50,9 @@ src_configure() {
 
 src_compile() {
 	# parallel build crashes
-	emake -j1 all
+	emake -j1 all CFLAGS="${CFLAGS}"
 	if use ocamlopt; then
-		emake -j1 opt
+		emake -j1 opt CFLAGS="${CFLAGS}"
 	fi
 }