diff --git a/nbdkit.spec b/nbdkit.spec
index 7d24b6a..f8965c8 100644
--- a/nbdkit.spec
+++ b/nbdkit.spec
@@ -39,6 +39,8 @@ BuildRequires:  autoconf, automake, libtool
 %endif
 BuildRequires:  /usr/bin/pod2man
 BuildRequires:  gnutls-devel
+# Only for running the test suite:
+BuildRequires:  /usr/bin/certtool
 BuildRequires:  libselinux-devel
 %if 0%{?have_libguestfs}
 BuildRequires:  libguestfs-devel