diff --git a/gi-docgen.spec b/gi-docgen.spec
index 82fbf64..826cc4d 100644
--- a/gi-docgen.spec
+++ b/gi-docgen.spec
@@ -170,7 +170,7 @@ find . -type f \( -name '*.woff' -o -name '*.woff2' \) -print -delete
 %pyproject_wheel
 
 %if %{with doc_pdf}
-sphinx-build -b latex %{?_smp_mflags} docs %{_vpath_builddir}/_latex
+sphinx-build -b latex -j%{?_smp_build_ncpus} docs %{_vpath_builddir}/_latex
 %make_build -C %{_vpath_builddir}/_latex LATEXMKOPTS='-quiet'
 %endif