diff --git a/solver/llbsolver/provenance.go b/solver/llbsolver/provenance.go
index 9138d6d9f88f..26abf78d1c6c 100644
--- a/solver/llbsolver/provenance.go
+++ b/solver/llbsolver/provenance.go
@@ -137,12 +137,14 @@ func (b *provenanceBridge) ResolveImageConfig(ctx context.Context, ref string, o
 		return "", "", nil, err
 	}
 
+	b.mu.Lock()
 	b.images = append(b.images, provenance.ImageSource{
 		Ref:      ref,
 		Platform: opt.Platform,
 		Digest:   dgst,
 		Local:    opt.ResolverType == llb.ResolverTypeOCILayout,
 	})
+	b.mu.Unlock()
 	return ref, dgst, config, nil
 }