diff --git a/avahi.spec b/avahi.spec
index 4dcea71..f6050ab 100644
--- a/avahi.spec
+++ b/avahi.spec
@@ -128,6 +128,7 @@ Summary:   Mono language bindings for avahi-ui mono development
 Group:            Development/Libraries
 Requires:  mono-core >= 1.1.13
 Requires:  gtk-sharp2
+BuildRequires:  gtk-sharp2-devel
 
 %description ui-sharp
 The avahi-sharp package contains the files needed to develop