diff --git a/modules/dnn/src/caffe/caffe_importer.cpp b/modules/dnn/src/caffe/caffe_importer.cpp
index 2d615c448a..0b6c0a6e38 100644
--- a/modules/dnn/src/caffe/caffe_importer.cpp
+++ b/modules/dnn/src/caffe/caffe_importer.cpp
@@ -49,6 +49,7 @@
 #include <google/protobuf/message.h>
 #include <google/protobuf/text_format.h>
 #include <google/protobuf/io/zero_copy_stream_impl.h>
+#include <google/protobuf/reflection.h>
 #include "caffe_io.hpp"
 #endif
 
@@ -57,8 +58,7 @@ namespace dnn {
 CV__DNN_EXPERIMENTAL_NS_BEGIN
 
 #ifdef HAVE_PROTOBUF
-using ::google::protobuf::RepeatedField;
-using ::google::protobuf::RepeatedPtrField;
+using ::google::protobuf::RepeatedFieldRef;
 using ::google::protobuf::Message;
 using ::google::protobuf::Descriptor;
 using ::google::protobuf::FieldDescriptor;
@@ -136,7 +136,7 @@ public:
 
         #define SET_UP_FILED(getter, arrayConstr, gtype)                                    \
             if (isRepeated) {                                                               \
-                const RepeatedField<gtype> &v = refl->GetRepeatedField<gtype>(msg, field);  \
+                const RepeatedFieldRef<gtype> v = refl->GetRepeatedFieldRef<gtype>(msg, field);  \
                 params.set(name, DictValue::arrayConstr(v.begin(), (int)v.size()));                  \
             }                                                                               \
             else {                                                                          \
@@ -168,7 +168,7 @@ public:
             break;
         case FieldDescriptor::CPPTYPE_STRING:
             if (isRepeated) {
-                const RepeatedPtrField<std::string> &v = refl->GetRepeatedPtrField<std::string>(msg, field);
+                const RepeatedFieldRef<std::string> v = refl->GetRepeatedFieldRef<std::string>(msg, field);
                 params.set(name, DictValue::arrayString(v.begin(), (int)v.size()));
             }
             else {
diff --git a/modules/dnn/src/tensorflow/tf_importer.cpp b/modules/dnn/src/tensorflow/tf_importer.cpp
index 16c5c16308..1a01ac87d6 100644
--- a/modules/dnn/src/tensorflow/tf_importer.cpp
+++ b/modules/dnn/src/tensorflow/tf_importer.cpp
@@ -2739,14 +2739,21 @@ DataLayout TFImporter::predictOutputDataLayout(const tensorflow::NodeDef& layer)
 
 void TFImporter::populateNet()
 {
-    CV_Assert(netBin.ByteSize() || netTxt.ByteSize());
+#if GOOGLE_PROTOBUF_VERSION < 3005000
+    size_t netBinSize = saturate_cast<size_t>(netBin.ByteSize());
+    size_t netTxtSize = saturate_cast<size_t>(netTxt.ByteSize());
+#else
+    size_t netBinSize = netBin.ByteSizeLong();
+    size_t netTxtSize = netTxt.ByteSizeLong();
+#endif
+    CV_Assert(netBinSize || netTxtSize);
 
     CV_LOG_INFO(NULL, "DNN/TF: parsing model"
         << (netBin.has_versions() ? cv::format(" produced by TF v%d (min_consumer=%d)", (int)netBin.versions().producer(), (int)netBin.versions().min_consumer()) : cv::String(" (N/A version info)"))
         << ". Number of nodes = " << netBin.node_size()
     );
 
-    if (netTxt.ByteSize())
+    if (netTxtSize)
     {
         CV_LOG_INFO(NULL, "DNN/TF: parsing config"
             << (netTxt.has_versions() ? cv::format(" produced by TF v%d (min_consumer=%d)", (int)netTxt.versions().producer(), (int)netTxt.versions().min_consumer()) : cv::String(" (N/A version info)"))
@@ -2775,7 +2782,7 @@ void TFImporter::populateNet()
         CV_LOG_DEBUG(NULL, "DNN/TF: sortByExecutionOrder(model) => " << netBin.node_size() << " nodes");
     }
 
-    tensorflow::GraphDef& net = netTxt.ByteSize() != 0 ? netTxt : netBin;
+    tensorflow::GraphDef& net = netTxtSize != 0 ? netTxt : netBin;
 
     int layersSize = net.node_size();
 
@@ -2873,7 +2880,12 @@ void TFImporter::addPermuteLayer(const int* order, const std::string& permName,
 
 void TFImporter::parseNode(const tensorflow::NodeDef& layer)
 {
-    tensorflow::GraphDef& net = netTxt.ByteSize() != 0 ? netTxt : netBin;
+#if GOOGLE_PROTOBUF_VERSION < 3005000
+    size_t netTxtSize = saturate_cast<size_t>(netTxt.ByteSize());
+#else
+    size_t netTxtSize = netTxt.ByteSizeLong();
+#endif
+    tensorflow::GraphDef& net = netTxtSize != 0 ? netTxt : netBin;
 
     const std::string& name = layer.name();
     const std::string& type = layer.op();