diff --git a/gnu/packages/golang-xyz.scm b/gnu/packages/golang-xyz.scm
index 6c7af0e7d25..075895d424a 100644
--- a/gnu/packages/golang-xyz.scm
+++ b/gnu/packages/golang-xyz.scm
@@ -9464,7 +9464,9 @@ GNU extensions} to the POSIX recommendations for command-line options.")
     (build-system go-build-system)
     (arguments
      (list
-      #:import-path "github.com/spf13/viper"))
+      #:import-path "github.com/spf13/viper"
+      ;; Optional modules are not packed.
+      #:test-subdirs #~(list ".")))
     (native-inputs
      (list go-github-com-stretchr-testify))
     (propagated-inputs