diff --git a/facter.spec b/facter.spec
index 54f8837..b86c63f 100644
--- a/facter.spec
+++ b/facter.spec
@@ -20,6 +20,7 @@ Requires:       ruby(rubygems)
 # Add runtime deps for testing
 BuildRequires:  (rubygem(hocon) >= 1.3 with rubygem(hocon) < 2)
 BuildRequires:  (rubygem(thor) >= 1.0.1 with rubygem(thor) < 2)
+BuildRequires:  rubygem(sys-filesystem)
 
 # Binaries that Facter can call for complete facts
 %ifarch %ix86 x86_64 ia64