diff --git a/s-nail.spec b/s-nail.spec
index 5e5d1bf..679002d 100644
--- a/s-nail.spec
+++ b/s-nail.spec
@@ -89,6 +89,10 @@ touch %{buildroot}%{_mandir}/man1/{Mail,mail,mailx,nail}.1
 
 
 %check
+%if %{defined rhel}
+# SHA-1 is disabled as insecure by RHEL default policies, but used in tests
+export OPENSSL_ENABLE_SHA1_SIGNATURES=yes
+%endif
 make test