diff --git a/src/common/gifdecod.cpp b/src/common/gifdecod.cpp
index 923685e552..4936609deb 100644
--- a/src/common/gifdecod.cpp
+++ b/src/common/gifdecod.cpp
@@ -476,7 +476,7 @@ int wxGIFDecoder::ReadGIF()
     int           ncolors, bits, interl, transparent, disposal, i;
     long          size;
     long          delay;
-    unsigned char type;
+    unsigned char type = 0;
     unsigned char pal[768];
     unsigned char buf[16];
     GIFImage      **ppimg, *pimg, *pprev;
diff --git a/src/common/imagjpeg.cpp b/src/common/imagjpeg.cpp
index 5e3f56ce34..6d4a1584fb 100644
--- a/src/common/imagjpeg.cpp
+++ b/src/common/imagjpeg.cpp
@@ -117,7 +117,7 @@ METHODDEF(void) my_term_source ( j_decompress_ptr cinfo )
     my_src_ptr src = (my_src_ptr) cinfo->src;
 
     if (src->pub.bytes_in_buffer > 0)
-        src->stream->SeekI(-src->pub.bytes_in_buffer, wxFromCurrent);
+        src->stream->SeekI(-(long)src->pub.bytes_in_buffer, wxFromCurrent);
     delete[] src->buffer;
 }
 
@@ -173,7 +173,11 @@ my_error_exit (j_common_ptr cinfo)
   longjmp(myerr->setjmp_buffer, 1);
 }
 
-
+// temporarily disable the warning C4611 (interaction between '_setjmp' and
+// C++ object destruction is non-portable) - I don't see any dtors here
+#ifdef __VISUALC__
+    #pragma warning(disable:4611)
+#endif /* VC++ */
 
 bool wxJPEGHandler::LoadFile( wxImage *image, wxInputStream& stream, bool verbose, int WXUNUSED(index) )
 {
@@ -229,10 +233,6 @@ bool wxJPEGHandler::LoadFile( wxImage *image, wxInputStream& stream, bool verbos
     return TRUE;
 }
 
-
-
-
-
 typedef struct {
     struct jpeg_destination_mgr pub;
 
@@ -339,6 +339,9 @@ bool wxJPEGHandler::SaveFile( wxImage *image, wxOutputStream& stream, bool verbo
     return TRUE;
 }
 
+#ifdef __VISUALC__
+    #pragma warning(default:4611)
+#endif /* VC++ */
 
 bool wxJPEGHandler::DoCanRead( wxInputStream& stream )
 {
diff --git a/src/common/imagpng.cpp b/src/common/imagpng.cpp
index f869ffedee..8272a0d383 100644
--- a/src/common/imagpng.cpp
+++ b/src/common/imagpng.cpp
@@ -93,6 +93,12 @@ LINKAGEMODE png_silent_warning(png_structp WXUNUSED(png_ptr), png_const_charp WX
 {
 }
 
+// temporarily disable the warning C4611 (interaction between '_setjmp' and
+// C++ object destruction is non-portable) - I don't see any dtors here
+#ifdef __VISUALC__
+    #pragma warning(disable:4611)
+#endif /* VC++ */
+
 bool wxPNGHandler::LoadFile( wxImage *image, wxInputStream& stream, bool verbose, int WXUNUSED(index) )
 {
     // VZ: as this function uses setjmp() the only fool proof error handling
@@ -267,7 +273,6 @@ bool wxPNGHandler::LoadFile( wxImage *image, wxInputStream& stream, bool verbose
     return FALSE;
 }
 
-
 bool wxPNGHandler::SaveFile( wxImage *image, wxOutputStream& stream, bool verbose )
 {
     {
@@ -346,6 +351,10 @@ bool wxPNGHandler::SaveFile( wxImage *image, wxOutputStream& stream, bool verbos
     return TRUE;
 }
 
+#ifdef __VISUALC__
+    #pragma warning(default:4611)
+#endif /* VC++ */
+
 bool wxPNGHandler::DoCanRead( wxInputStream& stream )
 {
     unsigned char hdr[4];
diff --git a/src/common/unzip.c b/src/common/unzip.c
index d9b855ae5c..be48958cfb 100644
--- a/src/common/unzip.c
+++ b/src/common/unzip.c
@@ -149,6 +149,11 @@ typedef struct
 int unzlocal_CheckCurrentFileCoherencyHeader (unz_s*, uInt*, uLong*, uInt*);
 #endif
 
+/* disable warnings about K&R declarations until the end of file */
+#ifdef _MSC_VER
+#pragma warning(disable:4131)
+#endif /* VC++ */
+
 /* ===========================================================================
      Read a byte from a gz_stream; update next_in and avail_in. Return EOF
    for end of file.