diff --git a/cmd/slsa-provenance/cli/files.go b/cmd/slsa-provenance/cli/files.go
index 09f1450c..d9371877 100644
--- a/cmd/slsa-provenance/cli/files.go
+++ b/cmd/slsa-provenance/cli/files.go
@@ -46,13 +46,11 @@ func Files() *cobra.Command {
 				Runner:  runner,
 			}
 
-			stmt, err := env.GenerateProvenanceStatement(cmd.Context(), artifactPath)
+			stmt, err := env.GenerateProvenanceStatement(cmd.Context(), artifactPath, materials...)
 			if err != nil {
 				return fmt.Errorf("failed to generate provenance: %w", err)
 			}
 
-			stmt.Predicate.Materials = append(stmt.Predicate.Materials, materials...)
-
 			fmt.Fprintf(cmd.OutOrStdout(), "Saving provenance to %s\n", outputPath)
 
 			return env.PersistProvenanceStatement(cmd.Context(), stmt, outputPath)
diff --git a/lib/github/provenance.go b/lib/github/provenance.go
index 94420b8f..381417cc 100644
--- a/lib/github/provenance.go
+++ b/lib/github/provenance.go
@@ -15,7 +15,7 @@ import (
 // GenerateProvenanceStatement generates provenance from the provided artifactPath
 //
 // The artifactPath can be a file or a directory.
-func (e *Environment) GenerateProvenanceStatement(ctx context.Context, artifactPath string) (*intoto.Statement, error) {
+func (e *Environment) GenerateProvenanceStatement(ctx context.Context, artifactPath string, materials ...intoto.Item) (*intoto.Statement, error) {
 	subjects, err := intoto.Subjects(artifactPath)
 	if os.IsNotExist(err) {
 		return nil, fmt.Errorf("resource path not found: [provided=%s]", artifactPath)
@@ -45,7 +45,9 @@ func (e *Environment) GenerateProvenanceStatement(ctx context.Context, artifactP
 			[]intoto.Item{
 				{URI: "git+" + repoURI, Digest: intoto.DigestSet{"sha1": e.Context.SHA}},
 			},
-		))
+		),
+		intoto.WithMaterials(materials),
+	)
 
 	return stmt, nil
 }
@@ -92,7 +94,7 @@ func NewReleaseEnvironment(gh Context, runner RunnerContext, tagName string, rc
 // Release assets will be downloaded to the given artifactPath
 //
 // The artifactPath has to be a directory.
-func (e *ReleaseEnvironment) GenerateProvenanceStatement(ctx context.Context, artifactPath string) (*intoto.Statement, error) {
+func (e *ReleaseEnvironment) GenerateProvenanceStatement(ctx context.Context, artifactPath string, materials ...intoto.Item) (*intoto.Statement, error) {
 	err := os.MkdirAll(artifactPath, 0755)
 	if err != nil {
 		return nil, err
@@ -117,7 +119,7 @@ func (e *ReleaseEnvironment) GenerateProvenanceStatement(ctx context.Context, ar
 		return nil, err
 	}
 
-	return e.Environment.GenerateProvenanceStatement(ctx, artifactPath)
+	return e.Environment.GenerateProvenanceStatement(ctx, artifactPath, materials...)
 }
 
 // PersistProvenanceStatement writes the provenance statement at the given path and uploads it to the GitHub release
diff --git a/lib/intoto/intoto.go b/lib/intoto/intoto.go
index 6a82f76e..2f5dd7a8 100644
--- a/lib/intoto/intoto.go
+++ b/lib/intoto/intoto.go
@@ -85,6 +85,13 @@ func WithInvocation(buildType, entryPoint string, environment json.RawMessage, p
 	}
 }
 
+// WithMaterials adds additional materials to the predicate
+func WithMaterials(materials []Item) StatementOption {
+	return func(s *Statement) {
+		s.Predicate.Materials = append(s.Predicate.Materials, materials...)
+	}
+}
+
 // Statement The Statement is the middle layer of the attestation, binding it to a particular subject and unambiguously identifying the types of the predicate.
 type Statement struct {
 	Type          string    `json:"_type"`