diff --git a/src/3rdparty/libpng.pri b/src/3rdparty/libpng.pri
index 7ac1910..81966cb 100644
--- a/src/3rdparty/libpng.pri
+++ b/src/3rdparty/libpng.pri
@@ -1,20 +1,7 @@
 DEFINES *= QT_USE_BUNDLED_LIBPNG
 !isEqual(QT_ARCH, i386):!isEqual(QT_ARCH, x86_64):DEFINES += PNG_NO_ASSEMBLER_CODE
 INCLUDEPATH += $$PWD/libpng
-SOURCES += $$PWD/libpng/png.c \
-  $$PWD/libpng/pngerror.c \
-  $$PWD/libpng/pngget.c \
-  $$PWD/libpng/pngmem.c \
-  $$PWD/libpng/pngpread.c \
-  $$PWD/libpng/pngread.c \
-  $$PWD/libpng/pngrio.c \
-  $$PWD/libpng/pngrtran.c \
-  $$PWD/libpng/pngrutil.c \
-  $$PWD/libpng/pngset.c \
-  $$PWD/libpng/pngtrans.c \
-  $$PWD/libpng/pngwio.c \
-  $$PWD/libpng/pngwrite.c \
-  $$PWD/libpng/pngwtran.c \
-  $$PWD/libpng/pngwutil.c
+
+SOURCES += $$PWD/libpng/privatepng.cpp
 
 include($$PWD/zlib_dependency.pri)
diff --git a/src/3rdparty/libpng/png.c b/src/3rdparty/libpng/png.c
index eed3136..db37732 100644
--- a/src/3rdparty/libpng/png.c
+++ b/src/3rdparty/libpng/png.c
@@ -13,6 +13,8 @@
 
 #include "pngpriv.h"
 
+namespace PrivatePng {
+
 /* Generate a compiler error if there is an old png.h in the search path. */
 typedef png_libpng_version_1_5_4 Your_png_h_is_not_version_1_5_4;
 
@@ -2420,3 +2422,4 @@ png_build_gamma_table(png_structp png_ptr, int bit_depth)
 }
 #endif /* READ_GAMMA */
 #endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */
+} // namespace PrivatePng
diff --git a/src/3rdparty/libpng/png.h b/src/3rdparty/libpng/png.h
index c655a51..69d9538 100644
--- a/src/3rdparty/libpng/png.h
+++ b/src/3rdparty/libpng/png.h
@@ -464,11 +464,6 @@
 
 #ifndef PNG_VERSION_INFO_ONLY
 
-/* Inhibit C++ name-mangling for libpng functions but not for system calls. */
-#ifdef __cplusplus
-extern "C" {
-#endif /* __cplusplus */
-
 /* Version information for C files, stored in png.c.  This had better match
  * the version above.
  */
@@ -520,6 +515,7 @@ extern "C" {
  * See pngconf.h for base types that vary by machine/system
  */
 
+namespace PrivatePng {
 /* This triggers a compiler error in png.c, if png.c and png.h
  * do not agree upon the version number.
  */
@@ -2579,10 +2575,7 @@ PNG_EXPORT(207, void, png_save_uint_16, (png_bytep buf, unsigned int i));
   PNG_EXPORT_LAST_ORDINAL(229);
 #endif
 
-#ifdef __cplusplus
-}
-#endif
-
 #endif /* PNG_VERSION_INFO_ONLY */
 /* Do not put anything past this line */
+} // namespace PrivatePng
 #endif /* PNG_H */
diff --git a/src/3rdparty/libpng/pngconf.h b/src/3rdparty/libpng/pngconf.h
index 2a41a29..99ce07f 100644
--- a/src/3rdparty/libpng/pngconf.h
+++ b/src/3rdparty/libpng/pngconf.h
@@ -64,6 +64,7 @@
 #  endif
 #endif
 
+namespace PrivatePng {
 /* COMPILER SPECIFIC OPTIONS.
  *
  * These options are provided so that a variety of difficult compilers
@@ -622,5 +623,5 @@ typedef char            FAR * FAR * FAR * png_charppp;
 #    endif
 #  endif
 #endif
-
+} // namespace PrivatePng
 #endif /* PNGCONF_H */
diff --git a/src/3rdparty/libpng/pngerror.c b/src/3rdparty/libpng/pngerror.c
index 4d4ceba..5559cfb 100644
--- a/src/3rdparty/libpng/pngerror.c
+++ b/src/3rdparty/libpng/pngerror.c
@@ -18,6 +18,8 @@
 
 #include "pngpriv.h"
 
+namespace PrivatePng {
+
 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
 
 static PNG_FUNCTION(void, png_default_error,PNGARG((png_structp png_ptr,
@@ -670,3 +672,5 @@ png_set_strip_error_numbers(png_structp png_ptr, png_uint_32 strip_mode)
 }
 #endif
 #endif /* PNG_READ_SUPPORTED || PNG_WRITE_SUPPORTED */
+} // namespace PrivatePng
+
diff --git a/src/3rdparty/libpng/pngget.c b/src/3rdparty/libpng/pngget.c
index b5e5798..0f18370 100644
--- a/src/3rdparty/libpng/pngget.c
+++ b/src/3rdparty/libpng/pngget.c
@@ -14,6 +14,8 @@
 
 #include "pngpriv.h"
 
+namespace PrivatePng {
+
 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
 
 png_uint_32 PNGAPI
@@ -1030,3 +1032,4 @@ png_get_io_chunk_name (png_structp png_ptr)
 #endif /* ?PNG_IO_STATE_SUPPORTED */
 
 #endif /* PNG_READ_SUPPORTED || PNG_WRITE_SUPPORTED */
+} // namespace PrivatePng
diff --git a/src/3rdparty/libpng/pnginfo.h b/src/3rdparty/libpng/pnginfo.h
index a33bfab..2ce4350 100644
--- a/src/3rdparty/libpng/pnginfo.h
+++ b/src/3rdparty/libpng/pnginfo.h
@@ -53,6 +53,7 @@
 #ifndef PNGINFO_H
 #define PNGINFO_H
 
+namespace PrivatePng {
 struct png_info_def
 {
    /* the following are necessary for every PNG file */
@@ -266,4 +267,6 @@ defined(PNG_READ_BACKGROUND_SUPPORTED)
 #endif
 
 };
+
+} // namespace PrivatePng
 #endif /* PNGINFO_H */
diff --git a/src/3rdparty/libpng/pngmem.c b/src/3rdparty/libpng/pngmem.c
index ea606d6..9f2e4df 100644
--- a/src/3rdparty/libpng/pngmem.c
+++ b/src/3rdparty/libpng/pngmem.c
@@ -19,6 +19,8 @@
 
 #include "pngpriv.h"
 
+namespace PrivatePng {
+
 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
 
 /* Borland DOS special memory handler */
@@ -665,3 +667,4 @@ png_get_mem_ptr(png_const_structp png_ptr)
 }
 #endif /* PNG_USER_MEM_SUPPORTED */
 #endif /* PNG_READ_SUPPORTED || PNG_WRITE_SUPPORTED */
+} // PrivatePng namespace
diff --git a/src/3rdparty/libpng/pngpread.c b/src/3rdparty/libpng/pngpread.c
index a50292a..26eb777 100644
--- a/src/3rdparty/libpng/pngpread.c
+++ b/src/3rdparty/libpng/pngpread.c
@@ -13,6 +13,8 @@
 
 #include "pngpriv.h"
 
+namespace PrivatePng {
+
 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
 
 /* Push model modes */
@@ -1854,3 +1856,4 @@ png_get_progressive_ptr(png_const_structp png_ptr)
    return png_ptr->io_ptr;
 }
 #endif /* PNG_PROGRESSIVE_READ_SUPPORTED */
+} // namespace PrivatePng
diff --git a/src/3rdparty/libpng/pngpriv.h b/src/3rdparty/libpng/pngpriv.h
index ca2fb8c..be4146d 100644
--- a/src/3rdparty/libpng/pngpriv.h
+++ b/src/3rdparty/libpng/pngpriv.h
@@ -46,6 +46,7 @@
 /* This is required for the definition of abort(), used as a last ditch
  * error handler when all else fails.
  */
+
 #include <stdlib.h>
 
 #define PNGLIB_BUILD
@@ -63,10 +64,12 @@
 #include "pnginfo.h"
 #include "pngstruct.h"
 
+namespace PrivatePng {
 /* This is used for 16 bit gamma tables - only the top level pointers are const,
  * this could be changed:
  */
 typedef PNG_CONST png_uint_16p FAR * png_const_uint_16pp;
+} // namespace PrivatePng
 
 /* Added at libpng-1.2.9 */
 /* Moved to pngpriv.h at libpng-1.5.0 */
@@ -429,6 +432,7 @@ typedef PNG_CONST png_uint_16p FAR * png_const_uint_16pp;
  * NOTE: by default this is off - the macro is not used - because the
  * function call saves a lot of code.
  */
+namespace PrivatePng {
 #ifdef PNG_FIXED_POINT_MACRO_SUPPORTED
 #define png_fixed(png_ptr, fp, s) ((fp) <= 21474 && (fp) >= -21474 ?\
     ((png_fixed_point)(100000 * (fp))) : (png_fixed_error(png_ptr, s),0))
@@ -437,6 +441,7 @@ PNG_EXTERN png_fixed_point png_fixed PNGARG((png_structp png_ptr, double fp,
    png_const_charp text));
 #endif
 #endif
+} // namespace PrivatePng
 
 /* Constant strings for known chunk types.  If you need to add a chunk,
  * define the name here, and add an invocation of the macro wherever it's
@@ -470,18 +475,14 @@ PNG_EXTERN png_fixed_point png_fixed PNGARG((png_structp png_ptr, double fp,
 #define PNG_GAMMA_MAC_INVERSE 65909
 #define PNG_GAMMA_sRGB_INVERSE 45455
 
-
-/* Inhibit C++ name-mangling for libpng functions but not for system calls. */
-#ifdef __cplusplus
-extern "C" {
-#endif /* __cplusplus */
-
 /* These functions are used internally in the code.  They generally
  * shouldn't be used unless you are writing code to add or replace some
  * functionality in libpng.  More information about most functions can
  * be found in the files where the functions are located.
  */
 
+namespace PrivatePng {
+
 /* Check the user version string for compatibility, returns false if the version
  * numbers aren't compatible.
  */
@@ -1355,10 +1356,8 @@ PNG_EXTERN void png_build_gamma_table PNGARG((png_structp png_ptr,
 /* Maintainer: Put new private prototypes here ^ and in libpngpf.3 */
 
 
-#include "pngdebug.h"
+} // PrivatePng
 
-#ifdef __cplusplus
-}
-#endif
+#include "pngdebug.h"
 
 #endif /* PNGPRIV_H */
diff --git a/src/3rdparty/libpng/pngread.c b/src/3rdparty/libpng/pngread.c
index be3df47..662dd4a 100644
--- a/src/3rdparty/libpng/pngread.c
+++ b/src/3rdparty/libpng/pngread.c
@@ -16,6 +16,8 @@
 
 #include "pngpriv.h"
 
+namespace PrivatePng {
+
 #ifdef PNG_READ_SUPPORTED
 
 /* Create a PNG structure for reading, and allocate any memory needed. */
@@ -1452,3 +1454,4 @@ png_read_png(png_structp png_ptr, png_infop info_ptr,
 #endif /* PNG_INFO_IMAGE_SUPPORTED */
 #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
 #endif /* PNG_READ_SUPPORTED */
+} // namespace PrivatePng
diff --git a/src/3rdparty/libpng/pngrio.c b/src/3rdparty/libpng/pngrio.c
index e9c381c..3a6e536 100644
--- a/src/3rdparty/libpng/pngrio.c
+++ b/src/3rdparty/libpng/pngrio.c
@@ -20,6 +20,7 @@
 
 #include "pngpriv.h"
 
+namespace PrivatePng {
 #ifdef PNG_READ_SUPPORTED
 
 /* Read the data from whatever input you are using.  The default routine
@@ -174,3 +175,4 @@ png_set_read_fn(png_structp png_ptr, png_voidp io_ptr,
 #endif
 }
 #endif /* PNG_READ_SUPPORTED */
+} // namespace PrivatePng
diff --git a/src/3rdparty/libpng/pngrtran.c b/src/3rdparty/libpng/pngrtran.c
index 4e0401a..d5b9d45 100644
--- a/src/3rdparty/libpng/pngrtran.c
+++ b/src/3rdparty/libpng/pngrtran.c
@@ -18,6 +18,8 @@
 
 #include "pngpriv.h"
 
+namespace PrivatePng {
+
 #ifdef PNG_READ_SUPPORTED
 
 /* Set the action on getting a CRC error for an ancillary or critical chunk. */
@@ -4951,3 +4953,4 @@ png_do_read_intrapixel(png_row_infop row_info, png_bytep row)
 }
 #endif /* PNG_MNG_FEATURES_SUPPORTED */
 #endif /* PNG_READ_SUPPORTED */
+} // namespace PrivatePng
diff --git a/src/3rdparty/libpng/pngrutil.c b/src/3rdparty/libpng/pngrutil.c
index 07e46e2..10484cb 100644
--- a/src/3rdparty/libpng/pngrutil.c
+++ b/src/3rdparty/libpng/pngrutil.c
@@ -16,6 +16,7 @@
 
 #include "pngpriv.h"
 
+namespace PrivatePng {
 #ifdef PNG_READ_SUPPORTED
 
 #define png_strtod(p,a,b) strtod(a,b)
@@ -458,7 +459,7 @@ png_decompress_chunk(png_structp png_ptr, int comp_type,
       {
          /* Success (maybe) - really uncompress the chunk. */
          png_size_t new_size = 0;
-         png_charp text = png_malloc_warn(png_ptr,
+         png_charp text = (png_charp) png_malloc_warn(png_ptr,
              prefix_size + expanded_size + 1);
 
          if (text != NULL)
@@ -501,7 +502,7 @@ png_decompress_chunk(png_structp png_ptr, int comp_type,
     * amount of compressed data.
     */
    {
-      png_charp text = png_malloc_warn(png_ptr, prefix_size + 1);
+      png_charp text = (png_charp) png_malloc_warn(png_ptr, prefix_size + 1);
 
       if (text != NULL)
       {
@@ -3664,3 +3665,4 @@ defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
    png_ptr->flags |= PNG_FLAG_ROW_INIT;
 }
 #endif /* PNG_READ_SUPPORTED */
+} // namespace PrivatePng
diff --git a/src/3rdparty/libpng/pngset.c b/src/3rdparty/libpng/pngset.c
index 7eaad7d..bb7c1ab 100644
--- a/src/3rdparty/libpng/pngset.c
+++ b/src/3rdparty/libpng/pngset.c
@@ -18,6 +18,8 @@
 
 #include "pngpriv.h"
 
+namespace PrivatePng {
+
 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
 
 #ifdef PNG_bKGD_SUPPORTED
@@ -1224,3 +1226,4 @@ png_set_benign_errors(png_structp png_ptr, int allowed)
 }
 #endif /* PNG_BENIGN_ERRORS_SUPPORTED */
 #endif /* PNG_READ_SUPPORTED || PNG_WRITE_SUPPORTED */
+} // namespace PrivatePng
diff --git a/src/3rdparty/libpng/pngstruct.h b/src/3rdparty/libpng/pngstruct.h
index 93b2b3e..d984461 100644
--- a/src/3rdparty/libpng/pngstruct.h
+++ b/src/3rdparty/libpng/pngstruct.h
@@ -26,6 +26,7 @@
  */
 #include "zlib.h"
 
+namespace PrivatePng {
 struct png_struct_def
 {
 #ifdef PNG_SETJMP_SUPPORTED
@@ -334,4 +335,5 @@ struct png_struct_def
    png_uint_32 io_state;
 #endif
 };
+} // namespace PrivatePng
 #endif /* PNGSTRUCT_H */
diff --git a/src/3rdparty/libpng/pngtest.c b/src/3rdparty/libpng/pngtest.c
index 9084ada..1a9f8db 100644
--- a/src/3rdparty/libpng/pngtest.c
+++ b/src/3rdparty/libpng/pngtest.c
@@ -32,13 +32,13 @@
  */
 
 #define _POSIX_SOURCE 1
-
 #include "zlib.h"
 #include "png.h"
 /* Copied from pngpriv.h but only used in error messages below. */
 #ifndef PNG_ZBUF_SIZE
 #  define PNG_ZBUF_SIZE 8192
 #endif
+
 #  include <stdio.h>
 #  include <stdlib.h>
 #  include <string.h>
@@ -99,8 +99,9 @@ static char tIME_string[PNG_tIME_STRING_LENGTH] = "tIME chunk is not present";
 
 static int verbose = 0;
 
+namespace PrivatePng {
 int test_one_file PNGARG((PNG_CONST char *inname, PNG_CONST char *outname));
-
+}
 #ifdef __TURBOC__
 #include <mem.h>
 #endif
@@ -114,6 +115,7 @@ int test_one_file PNGARG((PNG_CONST char *inname, PNG_CONST char *outname));
 #  define png_jmpbuf(png_ptr) png_ptr->jmpbuf
 #endif
 
+namespace PrivatePng {
 /* Example of using row callbacks to make a simple progress meter */
 static int status_pass = 1;
 static int status_dots_requested = 0;
@@ -1795,3 +1797,4 @@ main(int argc, char *argv[])
 
 /* Generate a compiler error if there is an old png.h in the search path. */
 typedef png_libpng_version_1_5_4 Your_png_h_is_not_version_1_5_4;
+} // namespace PrivatePng
diff --git a/src/3rdparty/libpng/pngtrans.c b/src/3rdparty/libpng/pngtrans.c
index 6a6908d..2e84686 100644
--- a/src/3rdparty/libpng/pngtrans.c
+++ b/src/3rdparty/libpng/pngtrans.c
@@ -13,6 +13,8 @@
 
 #include "pngpriv.h"
 
+namespace PrivatePng {
+
 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
 
 #if defined(PNG_READ_BGR_SUPPORTED) || defined(PNG_WRITE_BGR_SUPPORTED)
@@ -676,3 +678,4 @@ png_get_current_pass_number(png_const_structp png_ptr)
 #endif /* PNG_READ_USER_TRANSFORM_SUPPORTED ||
           PNG_WRITE_USER_TRANSFORM_SUPPORTED */
 #endif /* PNG_READ_SUPPORTED || PNG_WRITE_SUPPORTED */
+} // namespace PrivatePng
diff --git a/src/3rdparty/libpng/pngwio.c b/src/3rdparty/libpng/pngwio.c
index 95ffb34..3dc7378 100644
--- a/src/3rdparty/libpng/pngwio.c
+++ b/src/3rdparty/libpng/pngwio.c
@@ -20,6 +20,8 @@
 
 #include "pngpriv.h"
 
+namespace PrivatePng {
+
 #ifdef PNG_WRITE_SUPPORTED
 
 /* Write the data to whatever output you are using.  The default routine
@@ -252,3 +254,4 @@ void *png_far_to_near(png_structp png_ptr, png_voidp ptr, int check)
 #  endif
 #endif
 #endif /* PNG_WRITE_SUPPORTED */
+} // namespace PrivatePng
diff --git a/src/3rdparty/libpng/pngwrite.c b/src/3rdparty/libpng/pngwrite.c
index d1af9e8..a945eb8 100644
--- a/src/3rdparty/libpng/pngwrite.c
+++ b/src/3rdparty/libpng/pngwrite.c
@@ -13,6 +13,8 @@
 
 #include "pngpriv.h"
 
+namespace PrivatePng {
+
 #ifdef PNG_WRITE_SUPPORTED
 
 /* Writes all the PNG information.  This is the suggested way to use the
@@ -1653,3 +1655,4 @@ png_write_png(png_structp png_ptr, png_infop info_ptr,
 }
 #endif
 #endif /* PNG_WRITE_SUPPORTED */
+} // namespace PrivatePng
diff --git a/src/3rdparty/libpng/pngwtran.c b/src/3rdparty/libpng/pngwtran.c
index 124d708..1b36d01 100644
--- a/src/3rdparty/libpng/pngwtran.c
+++ b/src/3rdparty/libpng/pngwtran.c
@@ -13,6 +13,8 @@
 
 #include "pngpriv.h"
 
+namespace PrivatePng {
+
 #ifdef PNG_WRITE_SUPPORTED
 
 #ifdef PNG_WRITE_TRANSFORMS_SUPPORTED
@@ -631,3 +633,4 @@ png_do_write_intrapixel(png_row_infop row_info, png_bytep row)
 }
 #endif /* PNG_MNG_FEATURES_SUPPORTED */
 #endif /* PNG_WRITE_SUPPORTED */
+} // namespace PrivatePng
diff --git a/src/3rdparty/libpng/pngwutil.c b/src/3rdparty/libpng/pngwutil.c
index 3ae5ed4..1082350 100644
--- a/src/3rdparty/libpng/pngwutil.c
+++ b/src/3rdparty/libpng/pngwutil.c
@@ -13,6 +13,8 @@
 
 #include "pngpriv.h"
 
+namespace PrivatePng {
+
 #ifdef PNG_WRITE_SUPPORTED
 
 #ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED
@@ -3177,3 +3179,4 @@ png_write_filtered_row(png_structp png_ptr, png_bytep filtered_row)
 #endif
 }
 #endif /* PNG_WRITE_SUPPORTED */
+} // namespace PrivatePng
diff --git a/src/gui/image/qpnghandler.cpp b/src/gui/image/qpnghandler.cpp
index 7f5cbe8..adeadbb 100644
--- a/src/gui/image/qpnghandler.cpp
+++ b/src/gui/image/qpnghandler.cpp
@@ -53,6 +53,7 @@
 #ifdef QT_USE_BUNDLED_LIBPNG
 #include <../../3rdparty/libpng/png.h>
 #include <../../3rdparty/libpng/pngconf.h>
+using namespace PrivatePng;
 #else
 #include <png.h>
 #include <pngconf.h>
