diff --git a/ocaml-4.02.0.patch b/ocaml-4.02.0.patch
new file mode 100644
index 0000000..dea1175
--- /dev/null
+++ b/ocaml-4.02.0.patch
@@ -0,0 +1,11 @@
+--- a/ocamlutil/pretty.ml	
++++ a/ocamlutil/pretty.ml	
+@@ -640,7 +640,7 @@ external format_float: string -> float -> string = "caml_format_float"
+     
+ let gprintf (finish : doc -> 'b)  
+             (format : ('a, unit, doc, 'b) format4) : 'a =
+-  let format = (Obj.magic format : string) in
++  let format = string_of_format format in
+ 
+   (* Record the starting align depth *)
+   let startAlignDepth = !alignDepth in
diff --git a/ocaml-cil.spec b/ocaml-cil.spec
index 89da007..3951d4b 100644
--- a/ocaml-cil.spec
+++ b/ocaml-cil.spec
@@ -2,7 +2,7 @@
 
 Name:           ocaml-cil
 Version:        1.7.3
-Release:        7%{?dist}
+Release:        8%{?dist}
 Summary:        CIL - Infrastructure for C Program Analysis and Transformation
 License:        BSD
 
@@ -26,6 +26,10 @@ Patch2:         cil-1.7.3-enable-ocamlopt-g.patch
 # dependencies are calculated properly.
 Patch3:         cil-1.7.3-add-package-cilconfig.patch
 
+# Fix unsafe use of Obj.magic (upstream in > 1.7.3).
+# https://bugzilla.redhat.com/show_bug.cgi?id=1120273
+Patch4:         ocaml-4.02.0.patch
+
 %description
 CIL (C Intermediate Language) is a high-level representation along
 with a set of tools that permit easy analysis and source-to-source
@@ -107,6 +111,7 @@ for gcc.
 %patch1 -p1
 %patch2 -p1
 %patch3 -p1
+%patch4 -p1
 
 %build
 
@@ -181,8 +186,9 @@ rm -rf $RPM_BUILD_ROOT
 
 
 %changelog
-* Mon Jul 21 2014 Richard W.M. Jones <rjones@redhat.com> - 1.7.3-7
+* Mon Jul 21 2014 Richard W.M. Jones <rjones@redhat.com> - 1.7.3-8
 - OCaml 4.02.0 beta rebuild.
+- Add patch from upstream to fix hang during build on 4.02.0.
 
 * Thu Jun 19 2014 Richard W.M. Jones <rjones@redhat.com> - 1.7.3-6
 - Fix Perl broken dependencies.