diff --git a/examples/CMakeLists.txt b/examples/CMakeLists.txt
index c4dfe6ffb..aa3114776 100644
--- a/examples/CMakeLists.txt
+++ b/examples/CMakeLists.txt
@@ -13,6 +13,9 @@ if(NOT OpenCV_FOUND)
 endif()
 
 if(OpenCV_FOUND)
+    if(${OpenCV_VERSION_MAJOR} GREATER_EQUAL 4)
+        set(CMAKE_CXX_STANDARD 11)
+    endif()
     include_directories(${CMAKE_CURRENT_SOURCE_DIR}/../src)
     include_directories(${CMAKE_CURRENT_BINARY_DIR}/../src)
 
diff --git a/tools/darknet/darknet2ncnn.cpp b/tools/darknet/darknet2ncnn.cpp
index 184ec2bd2..ef10646dc 100644
--- a/tools/darknet/darknet2ncnn.cpp
+++ b/tools/darknet/darknet2ncnn.cpp
@@ -472,7 +472,7 @@ void parse_cfg(std::deque<Section*>& dnet, int merge_output)
             s->w = p->out_w;
             s->c = p->out_c;
             s->out_h = (s->h + s->padding - s->size) / s->stride + 1;
-            s->out_w = s->out_h;
+            s->out_w = (s->w + s->padding - s->size) / s->stride + 1;
             s->out_c = s->c;
 
 #if OUTPUT_LAYER_MAP