diff --git a/sdks/go/pkg/beam/runners/prism/internal/preprocess.go b/sdks/go/pkg/beam/runners/prism/internal/preprocess.go
index 6648941484e5..cb1fcc30f070 100644
--- a/sdks/go/pkg/beam/runners/prism/internal/preprocess.go
+++ b/sdks/go/pkg/beam/runners/prism/internal/preprocess.go
@@ -43,6 +43,9 @@ func newPreprocessor(preps []transformPreparer) *preprocessor {
 	}
 }
 
+// transformPreparer is an interface for handling different urns in the prepropcessor
+// largely for exchanging transforms for others, to be added to the complete set of
+// components in the pipeline.
 type transformPreparer interface {
 	// PrepareUrns returns the Beam URNs that this handler deals with for preprocessing.
 	PrepareUrns() []string