diff --git a/graphviz-2.42.2-ocaml-allow-const-cast.patch b/graphviz-2.42.2-ocaml-allow-const-cast.patch
new file mode 100644
index 0000000..31af6da
--- /dev/null
+++ b/graphviz-2.42.2-ocaml-allow-const-cast.patch
@@ -0,0 +1,15 @@
+--- graphviz-stable_release_2.42.2/tclpkg/gv/Makefile.am	2019-09-12 03:11:30.000000000 +0100
++++ graphviz-stable_release_2.42.2.new/tclpkg/gv/Makefile.am	2019-12-06 13:05:44.064150008 +0000
+@@ -130,7 +130,11 @@
+ libgv_ocaml_la_SOURCES = $(BASESOURCES) gv_dummy_init.c
+ libgv_ocaml_la_LIBADD = $(BASELIBS) $(OCAML_LIBS)
+ libgv_ocaml_la_LDFLAGS = -module -avoid-version
+-libgv_ocaml_la_CPPFLAGS = $(BASECPPFLAGS) $(OCAML_INCLUDES) -Dint64=int64_t
++libgv_ocaml_la_CPPFLAGS = \
++	$(BASECPPFLAGS) \
++	$(OCAML_INCLUDES) \
++	-Dint64=int64_t \
++	-fpermissive
+ gv.ml gv.mli: gv_ocaml.cpp
+ gv_ocaml.cpp: gv.i
+ 	$(SWIG) -c++ -ocaml -o gv_ocaml.cpp $(srcdir)/gv.i
diff --git a/graphviz.spec b/graphviz.spec
index 3579163..3f6beec 100644
--- a/graphviz.spec
+++ b/graphviz.spec
@@ -73,6 +73,9 @@ Source0:		https://gitlab.com/%{name}/%{name}/-/archive/stable_release_%{version}
 # rhbz#1505230
 Patch0:			graphviz-2.42.2-dotty-menu-fix.patch
 Patch1:			graphviz-2.42.2-coverity-scan-fixes.patch
+# Workaround for some const casting badness in the OCaml bindings.
+# Real fix will need a fix to SWIG.
+Patch2:                 graphviz-2.42.2-ocaml-allow-const-cast.patch
 BuildRequires:		zlib-devel, libpng-devel, libjpeg-devel, expat-devel, freetype-devel >= 2
 BuildRequires:		ksh, bison, m4, flex, tk-devel, tcl-devel >= 8.3, swig, sed
 BuildRequires:		fontconfig-devel, libtool-ltdl-devel, ruby-devel, ruby, guile-devel
@@ -286,6 +289,7 @@ Various tcl packages (extensions) for the graphviz tools.
 %setup -q -n graphviz-stable_release_%{version}
 %patch0 -p1 -b .dotty-menu-fix
 %patch1 -p1 -b .coverity-scan-fixes
+%patch2 -p1
 
 # Attempt to fix rpmlint warnings about executable sources
 find -type f -regex '.*\.\(c\|h\)$' -exec chmod a-x {} ';'