diff --git a/solver/errdefs/op.go b/solver/errdefs/op.go
index a3c448a06..61068b6e4 100644
--- a/solver/errdefs/op.go
+++ b/solver/errdefs/op.go
@@ -11,9 +11,10 @@ func (e *OpError) Unwrap() error {
 	return e.error
 }
 
-func WithOp(err error, op *pb.Op) error {
-	if err == nil {
-		return nil
+func WithOp(err error, iface interface{}) error {
+	op, ok := iface.(*pb.Op)
+	if err == nil || !ok {
+		return err
 	}
 	return &OpError{error: err, Op: op}
 }
diff --git a/solver/jobs.go b/solver/jobs.go
index fc4c1f8ce..932d9d0f1 100644
--- a/solver/jobs.go
+++ b/solver/jobs.go
@@ -10,7 +10,6 @@ import (
 	"github.com/moby/buildkit/client"
 	"github.com/moby/buildkit/session"
 	"github.com/moby/buildkit/solver/errdefs"
-	"github.com/moby/buildkit/solver/pb"
 	"github.com/moby/buildkit/util/flightcontrol"
 	"github.com/moby/buildkit/util/progress"
 	"github.com/moby/buildkit/util/tracing"
@@ -623,7 +622,7 @@ func (s *sharedOp) LoadCache(ctx context.Context, rec *CacheRecord) (Result, err
 func (s *sharedOp) CalcSlowCache(ctx context.Context, index Index, p PreprocessFunc, f ResultBasedCacheFunc, res Result) (dgst digest.Digest, err error) {
 	defer func() {
 		err = WrapSlowCache(err, index, NewSharedResult(res).Clone())
-		err = errdefs.WithOp(err, s.st.vtx.Sys().(*pb.Op))
+		err = errdefs.WithOp(err, s.st.vtx.Sys())
 		err = errdefs.WrapVertex(err, s.st.origDigest)
 	}()
 	key, err := s.g.Do(ctx, fmt.Sprintf("slow-compute-%d", index), func(ctx context.Context) (interface{}, error) {
@@ -686,7 +685,7 @@ func (s *sharedOp) CalcSlowCache(ctx context.Context, index Index, p PreprocessF
 
 func (s *sharedOp) CacheMap(ctx context.Context, index int) (resp *cacheMapResp, err error) {
 	defer func() {
-		err = errdefs.WithOp(err, s.st.vtx.Sys().(*pb.Op))
+		err = errdefs.WithOp(err, s.st.vtx.Sys())
 		err = errdefs.WrapVertex(err, s.st.origDigest)
 	}()
 	op, err := s.getOp()
@@ -745,7 +744,7 @@ func (s *sharedOp) CacheMap(ctx context.Context, index int) (resp *cacheMapResp,
 
 func (s *sharedOp) Exec(ctx context.Context, inputs []Result) (outputs []Result, exporters []ExportableCacheKey, err error) {
 	defer func() {
-		err = errdefs.WithOp(err, s.st.vtx.Sys().(*pb.Op))
+		err = errdefs.WithOp(err, s.st.vtx.Sys())
 		err = errdefs.WrapVertex(err, s.st.origDigest)
 	}()
 	op, err := s.getOp()