diff --git a/.gitignore b/.gitignore
index b1d57a3..54c1268 100644
--- a/.gitignore
+++ b/.gitignore
@@ -9,3 +9,4 @@ ocamlnet-2.2.9.tar.gz
 /ocamlnet-4.0.4.tar.gz
 /ocamlnet-4.1.2.tar.gz
 /ocamlnet-4.1.3.tar.gz
+/ocamlnet-4.1.4.tar.gz
diff --git a/ocaml-ocamlnet.spec b/ocaml-ocamlnet.spec
index 09e6405..d9e4a8e 100644
--- a/ocaml-ocamlnet.spec
+++ b/ocaml-ocamlnet.spec
@@ -1,5 +1,3 @@
-%global opt %(test -x %{_bindir}/ocamlopt && echo 1 || echo 0)
-
 # Prevent RPM from stripping the binaries & debuginfo.
 #
 # NB: Only required because this package uses the obsolete -custom
@@ -10,14 +8,16 @@
 %global __strip /bin/true
 
 Name:           ocaml-ocamlnet
-Version:        4.1.3
-Release:        4%{?dist}
+Version:        4.1.4
+Release:        1%{?dist}
 Summary:        Network protocols for OCaml
 License:        BSD
 
 URL:            http://projects.camlcity.org/projects/ocamlnet.html
 Source0:        http://download.camlcity.org/download/ocamlnet-%{version}.tar.gz
 
+# Non-upstream patch to fix string immutability problems with OCaml 4.06.
+Patch1:         ocamlnet-4.1.4-bytes-fixes.patch
 
 BuildRequires:  ocaml >= 3.12.1-3
 BuildRequires:  ocaml-ocamldoc
@@ -111,6 +111,7 @@ files for developing applications that use %{name}-nethttpd.
 
 %prep
 %setup -q -n ocamlnet-%{version}
+%autopatch -p1
 
 
 %build
@@ -131,7 +132,7 @@ unset MAKEFLAGS
 
 make all
 
-%if %opt
+%ifarch %{ocaml_native_compiler}
 make opt
 %endif
 
@@ -175,7 +176,7 @@ echo -e '-b /usr/bin/netplex-admin\n-b /usr/bin/ocamlrpcgen' \
 %{_libdir}/ocaml/rpc-auth-local
 %{_libdir}/ocaml/rpc-generator
 %{_libdir}/ocaml/shell
-%if %opt
+%ifarch %{ocaml_native_compiler}
 %exclude %{_libdir}/ocaml/*/*.a
 %exclude %{_libdir}/ocaml/*/*.cmxa
 %exclude %{_libdir}/ocaml/*/*.cmx
@@ -192,7 +193,7 @@ echo -e '-b /usr/bin/netplex-admin\n-b /usr/bin/ocamlrpcgen' \
 
 %files devel
 %doc ChangeLog RELNOTES
-%if %opt
+%ifarch %{ocaml_native_compiler}
 %{_libdir}/ocaml/*/*.a
 %{_libdir}/ocaml/*/*.cmxa
 %{_libdir}/ocaml/*/*.cmx
@@ -204,7 +205,7 @@ echo -e '-b /usr/bin/netplex-admin\n-b /usr/bin/ocamlrpcgen' \
 %files nethttpd
 %doc ChangeLog RELNOTES
 %{_libdir}/ocaml/nethttpd
-%if %opt
+%ifarch %{ocaml_native_compiler}
 %exclude %{_libdir}/ocaml/*/*.a
 %exclude %{_libdir}/ocaml/*/*.cmxa
 %endif
@@ -213,7 +214,7 @@ echo -e '-b /usr/bin/netplex-admin\n-b /usr/bin/ocamlrpcgen' \
 
 %files nethttpd-devel
 %doc ChangeLog RELNOTES
-%if %opt
+%ifarch %{ocaml_native_compiler}
 %{_libdir}/ocaml/*/*.a
 %{_libdir}/ocaml/*/*.cmxa
 %endif
@@ -221,11 +222,8 @@ echo -e '-b /usr/bin/netplex-admin\n-b /usr/bin/ocamlrpcgen' \
 
 
 %changelog
-* Wed Nov 08 2017 Richard W.M. Jones <rjones@redhat.com> - 4.1.3-4
-- Bump release and rebuild.
-
-* Wed Nov 08 2017 Richard W.M. Jones <rjones@redhat.com> - 4.1.3-3
-- Bump release and rebuild.
+* Wed Nov 08 2017 Richard W.M. Jones <rjones@redhat.com> - 4.1.4-1
+- New upstream version 4.1.4.
 
 * Tue Nov 07 2017 Richard W.M. Jones <rjones@redhat.com> - 4.1.3-2
 - OCaml 4.06.0 rebuild.
diff --git a/ocamlnet-4.1.4-bytes-fixes.patch b/ocamlnet-4.1.4-bytes-fixes.patch
new file mode 100644
index 0000000..4c832a0
--- /dev/null
+++ b/ocamlnet-4.1.4-bytes-fixes.patch
@@ -0,0 +1,54 @@
+--- ocamlnet-4.1.4.old/src/netzip/netgzip.ml	2017-08-14 14:16:50.000000000 +0100
++++ ocamlnet-4.1.4/src/netzip/netgzip.ml	2017-11-08 16:24:22.162165338 +0000
+@@ -7,7 +7,6 @@
+   val mutable closed = false
+ 
+   method input s p l = 
+-    let s = Bytes.unsafe_to_string s in
+     let n = Gzip.input gzip_ch s p l in
+     if n = 0 then raise End_of_file;
+     n
+@@ -27,7 +26,6 @@
+ class output_gzip_rec gzip_ch : Netchannels.rec_out_channel =
+ object(self)
+   method output s p l =
+-    let s = Bytes.unsafe_to_string s in
+     Gzip.output gzip_ch s p l;
+     l
+   method close_out() =
+@@ -156,8 +154,6 @@
+ 		          (fun out_buf out_pos out_len ->
+ 		             let (finished, used_in, used_out) =
+ 			       try
+-                                 let in_buf = Bytes.unsafe_to_string in_buf in
+-                                 let out_buf = Bytes.unsafe_to_string out_buf in
+ 			         Zlib.inflate 
+ 			           stream 
+                                    in_buf in_pos in_len out_buf out_pos out_len 
+@@ -170,8 +166,7 @@
+                              st.in_size <-
+ 			       Int32.add st.in_size (Int32.of_int used_out);
+ 		             st.in_crc <-
+-                               ( let out_buf = Bytes.unsafe_to_string out_buf in
+-			         Zlib.update_crc st.in_crc out_buf out_pos used_out
++                               ( Zlib.update_crc st.in_crc out_buf out_pos used_out
+                                );
+ 		       
+ 		             k := !k + used_in;
+@@ -292,8 +287,6 @@
+ 		  (fun out_buf out_pos out_len ->
+ 		     let (finished, used_in, used_out) =
+ 		       try
+-                         let in_buf = Bytes.unsafe_to_string in_buf in
+-                         let out_buf = Bytes.unsafe_to_string out_buf in
+ 			 Zlib.deflate 
+ 			   stream in_buf 0 in_len out_buf out_pos out_len 
+ 			   (if at_eof then Zlib.Z_FINISH else Zlib.Z_NO_FLUSH)
+@@ -305,7 +298,6 @@
+ 		     
+ 		     st.out_size <- Int32.add st.out_size (Int32.of_int used_in);
+ 		     st.out_crc <- (
+-                       let in_buf = Bytes.unsafe_to_string in_buf in
+                        Zlib.update_crc st.out_crc in_buf 0 used_in
+                      );
+ 		     
diff --git a/sources b/sources
index 2e29d3d..06dc763 100644
--- a/sources
+++ b/sources
@@ -1 +1 @@
-SHA512 (ocamlnet-4.1.3.tar.gz) = 683ab6f529639c9da01478ba8ba7a1bf89a418ad3872331bb3e29067c0a75ddc0db996630ce5a5dd116967d6e3e756ade02d9a78b865bbc226f95d01af9e3956
+SHA512 (ocamlnet-4.1.4.tar.gz) = ca502444f81898ccda27d61760a357aad59624cf3c4c025d49dd1c2e7bc3ef497c199634247ba7731e016c234e5cd92d2599d1ef9ecd55c3b6e7a64fc4773ee0