diff --git a/ocaml-calendar-buildcompare.patch b/ocaml-calendar-buildcompare.patch
new file mode 100644
index 0000000..f770c60
--- /dev/null
+++ b/ocaml-calendar-buildcompare.patch
@@ -0,0 +1,15 @@
+---
+ Makefile.in |    2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+--- a/Makefile.in
++++ b/Makefile.in
+@@ -117,7 +117,7 @@ $(LIBDIR)/$(NAMELIB).cmxs: $(LIBDIR)/$(N
+ 
+ src/version.ml: Makefile
+ 	echo "let version = \"$(VERSION)\"" > $@
+-	echo "let date = \"`date`\"" >> $@
++	echo "let date = \"`date --reference=CHANGES`\"" >> $@
+ 
+ META: Makefile
+ 	echo "name = \"$(NAME)\"" > $@
diff --git a/ocaml-calendar.spec b/ocaml-calendar.spec
index 6a2bb92..4a7cb53 100644
--- a/ocaml-calendar.spec
+++ b/ocaml-calendar.spec
@@ -31,6 +31,7 @@ Group:          Development/Libraries/Other
 Url:            http://calendar.forge.ocamlcore.org/
 Source0:        http://forge.ocamlcore.org/frs/download.php/1481/calendar-2.04.tar.gz
 Patch1:         calendar-2.04-enable-debug.patch
+Patch2:         ocaml-calendar-buildcompare.patch
 BuildRequires:  gawk
 BuildRequires:  ocaml >= 4.00.1
 BuildRequires:  ocaml-rpm-macros >= 4.02.1
@@ -59,6 +60,7 @@ developing applications that use %{name}.
 %prep
 %setup -q -n calendar-%{version}
 %patch1 -p1
+%patch2 -p1
 
 
 %build