diff --git a/gnu/packages/statistics.scm b/gnu/packages/statistics.scm
index 66556d0d9e..437b8455a9 100644
--- a/gnu/packages/statistics.scm
+++ b/gnu/packages/statistics.scm
@@ -6977,7 +6977,7 @@ (define-public r-nnlm
       (properties `((upstream-name . "NNLM")))
       (build-system r-build-system)
       (propagated-inputs (list r-rcpp r-rcpparmadillo r-rcppprogress))
-      (native-inputs (list r-knitr))
+      (native-inputs (list r-knitr r-testthat))
       (home-page "https://github.com/linxihui/NNLM")
       (synopsis "Fast and versatile non-negative matrix factorization")
       (description