diff --git a/debian/control b/debian/control
index 508b12a65..7f20d1028 100644
--- a/debian/control
+++ b/debian/control
@@ -1,14 +1,14 @@
 Source: sogo
 Priority: optional
 Maintainer: Inverse Support <support@inverse.ca>
-Build-Depends: debhelper (>= 7.0.15), gobjc | objc-compiler, libgnustep-base-dev, libsope-appserver4.9-dev, libsope-core4.9-dev, libsope-gdl1-4.9-dev, libsope-ldap4.9-dev, libsope-mime4.9-dev, libsope-xml4.9-dev, libmemcached-dev, libxml2-dev, libsbjson-dev, libssl-dev
+Build-Depends: debhelper (>= 7.0.15), gobjc | objc-compiler, libgnustep-base-dev, libsope-appserver4.9-dev, libsope-core4.9-dev, libsope-gdl1-4.9-dev, libsope-ldap4.9-dev, libsope-mime4.9-dev, libsope-xml4.9-dev, libmemcached-dev, libxml2-dev, libsbjson-dev, libssl-dev, libcurl4-openssl-dev | libcurl4-gnutls-dev
 Section: web
 Standards-Version: 3.9.1
 
 Package: sogo
 Section: web
 Architecture: any
-Depends: ${shlibs:Depends}, ${misc:Depends}, tmpreaper, sope4.9-libxmlsaxdriver, sope4.9-db-connector, gnustep-make
+Depends: ${shlibs:Depends}, ${misc:Depends}, tmpreaper, sope4.9-libxmlsaxdriver, sope4.9-db-connector, gnustep-make, libcurl3
 Suggests: nginx
 Description: a modern and scalable groupware
  SOGo is a groupware server built around OpenGroupware.org (OGo) and
diff --git a/sogo.spec b/sogo.spec
index e6f3590f7..65129011d 100644
--- a/sogo.spec
+++ b/sogo.spec
@@ -17,7 +17,14 @@ Prefix:       /usr
 AutoReqProv:  off
 Requires:     gnustep-base >= 1.23, sope%{sope_major_version}%{sope_minor_version}-core, httpd, sope%{sope_major_version}%{sope_minor_version}-core, sope%{sope_major_version}%{sope_minor_version}-appserver, sope%{sope_major_version}%{sope_minor_version}-ldap, sope%{sope_major_version}%{sope_minor_version}-cards >= %{sogo_version}, sope%{sope_major_version}%{sope_minor_version}-gdl1-contentstore >= %{sogo_version}, sope%{sope_major_version}%{sope_minor_version}-sbjson, memcached, libmemcached
 BuildRoot:    %{_tmppath}/%{name}-%{version}-%{release}
-BuildPreReq:  gcc-objc gnustep-base gnustep-make sope%{sope_major_version}%{sope_minor_version}-appserver-devel sope%{sope_major_version}%{sope_minor_version}-core-devel sope%{sope_major_version}%{sope_minor_version}-ldap-devel sope%{sope_major_version}%{sope_minor_version}-mime-devel sope%{sope_major_version}%{sope_minor_version}-xml-devel sope%{sope_major_version}%{sope_minor_version}-gdl1-devel sope%{sope_major_version}%{sope_minor_version}-sbjson-devel libmemcached-devel %{?oc_build_depends}
+BuildRequires:  gcc-objc gnustep-base gnustep-make sope%{sope_major_version}%{sope_minor_version}-appserver-devel sope%{sope_major_version}%{sope_minor_version}-core-devel sope%{sope_major_version}%{sope_minor_version}-ldap-devel sope%{sope_major_version}%{sope_minor_version}-mime-devel sope%{sope_major_version}%{sope_minor_version}-xml-devel sope%{sope_major_version}%{sope_minor_version}-gdl1-devel sope%{sope_major_version}%{sope_minor_version}-sbjson-devel libmemcached-devel %{?oc_build_depends}
+
+
+# Required by MS Exchange freebusy lookups
+%{?el5:Requires: curl}
+%{?el5:BuildRequires: curl-devel}
+%{?el6:Requires: libcurl}
+%{?el6:BuildRequires: libcurl-devel}
 
 %description
 SOGo is a groupware server built around OpenGroupware.org (OGo) and