diff --git a/3rdparty/libjpeg/CMakeLists.txt b/3rdparty/libjpeg/CMakeLists.txt
index 969cd99e75..b323255f06 100644
--- a/3rdparty/libjpeg/CMakeLists.txt
+++ b/3rdparty/libjpeg/CMakeLists.txt
@@ -38,7 +38,7 @@ if(CMAKE_COMPILER_IS_GNUCXX)
   set_source_files_properties(jcdctmgr.c PROPERTIES COMPILE_FLAGS "-O1")
 endif()
 
-ocv_warnings_disable(CMAKE_C_FLAGS -Wcast-align -Wshadow -Wunused)
+ocv_warnings_disable(CMAKE_C_FLAGS -Wcast-align -Wshadow -Wunused -Wshift-negative-value)
 ocv_warnings_disable(CMAKE_C_FLAGS -Wunused-parameter) # clang
 ocv_warnings_disable(CMAKE_C_FLAGS /wd4013 /wd4244 /wd4267) # vs2005
 
diff --git a/modules/videoio/src/cap_dc1394_v2.cpp b/modules/videoio/src/cap_dc1394_v2.cpp
index b3fc18c50c..0d674fe179 100644
--- a/modules/videoio/src/cap_dc1394_v2.cpp
+++ b/modules/videoio/src/cap_dc1394_v2.cpp
@@ -603,9 +603,9 @@ bool CvCaptureCAM_DC1394_v2_CPP::grabFrame()
         cvInitImageHeader(&fhdr, cvSize(fc->size[0], fc->size[1]), 8, nch);
         cvSetData(&fhdr, fc->image, fc->size[0]*nch);
 
-    // Swap R&B channels:
-    if (nch==3)
-        cvConvertImage(&fhdr,&fhdr,CV_CVTIMG_SWAP_RB);
+        // Swap R&B channels:
+        if (nch==3)
+            cvConvertImage(&fhdr,&fhdr,CV_CVTIMG_SWAP_RB);
 
         if( rectify && cameraId == VIDERE && nimages == 2 )
         {