diff --git a/pkg/build/buildkit/buildx.go b/pkg/build/buildkit/buildx.go
index f96a594dd..2c080021c 100644
--- a/pkg/build/buildkit/buildx.go
+++ b/pkg/build/buildkit/buildx.go
@@ -220,28 +220,3 @@ func (b *Builder) TagInvocationImage(ctx context.Context, origTag, newTag string
 	}
 	return nil
 }
-
-func convertMap(mapInput map[string]interface{}) (map[string]string, error) {
-	out := make(map[string]string)
-	for key, value := range mapInput {
-		switch v := value.(type) {
-		case string:
-			out[key] = v
-		case map[string]interface{}:
-			tmp, err := convertMap(v)
-			if err != nil {
-				return nil, err
-			}
-			for innerKey, innerValue := range tmp {
-				out[key+"."+innerKey] = innerValue
-			}
-		case map[string]string:
-			for innerKey, innerValue := range v {
-				out[key+"."+innerKey] = innerValue
-			}
-		default:
-			return nil, errors.Errorf("Unknown type %#v: %t", v, v)
-		}
-	}
-	return out, nil
-}