diff --git a/libguestfs.spec b/libguestfs.spec
index 07b073b..f232dd3 100644
--- a/libguestfs.spec
+++ b/libguestfs.spec
@@ -123,6 +123,7 @@ BuildRequires: python3-devel
 BuildRequires: libvirt-python3
 BuildRequires: ruby-devel
 BuildRequires: rubygem-rake
+BuildRequires: rubygem(json)  # RHBZ#1325022
 BuildRequires: rubygem(rdoc)
 BuildRequires: rubygem(test-unit)
 BuildRequires: ruby-irb