diff --git a/Tests/check_large_memory.py b/Tests/check_large_memory.py
index 24d687ea692..a2fcc206e28 100644
--- a/Tests/check_large_memory.py
+++ b/Tests/check_large_memory.py
@@ -12,6 +12,12 @@
 # 2.7 and 3.2.
 
 from PIL import Image
+
+try:
+    import numpy
+except ImportError:
+    numpy = None
+
 YDIM = 32769
 XDIM = 48000
 
@@ -32,6 +38,11 @@ def test_2gpx(self):
         """failed prepatch"""
         self._write_png(XDIM, XDIM)
 
+    @unittest.skipIf(numpy is None, "Numpy is not installed")
+    def test_size_greater_than_int(self):
+        arr = numpy.ndarray(shape=(16394, 16394))
+        Image.fromarray(arr)
+
 
 if __name__ == '__main__':
     unittest.main()
diff --git a/src/decode.c b/src/decode.c
index 562bc743699..10e740aaf4e 100644
--- a/src/decode.c
+++ b/src/decode.c
@@ -48,7 +48,7 @@
 typedef struct {
     PyObject_HEAD
     int (*decode)(Imaging im, ImagingCodecState state,
-                  UINT8* buffer, int bytes);
+                  UINT8* buffer, Py_ssize_t bytes);
     int (*cleanup)(ImagingCodecState state);
     struct ImagingCodecStateInstance state;
     Imaging im;
diff --git a/src/libImaging/BcnDecode.c b/src/libImaging/BcnDecode.c
index 1472b02961c..c2c4f21e7c3 100644
--- a/src/libImaging/BcnDecode.c
+++ b/src/libImaging/BcnDecode.c
@@ -844,7 +844,7 @@ static int decode_bcn(Imaging im, ImagingCodecState state, const UINT8* src, int
 	return (int)(ptr - src);
 }
 
-int ImagingBcnDecode(Imaging im, ImagingCodecState state, UINT8* buf, int bytes) {
+int ImagingBcnDecode(Imaging im, ImagingCodecState state, UINT8* buf, Py_ssize_t bytes) {
 	int N = state->state & 0xf;
 	int width = state->xsize;
 	int height = state->ysize;
diff --git a/src/libImaging/BitDecode.c b/src/libImaging/BitDecode.c
index a78183542d2..7120b332138 100644
--- a/src/libImaging/BitDecode.c
+++ b/src/libImaging/BitDecode.c
@@ -20,7 +20,7 @@
 
 
 int
-ImagingBitDecode(Imaging im, ImagingCodecState state, UINT8* buf, int bytes)
+ImagingBitDecode(Imaging im, ImagingCodecState state, UINT8* buf, Py_ssize_t bytes)
 {
     BITSTATE* bitstate = state->context;
     UINT8* ptr;
diff --git a/src/libImaging/FliDecode.c b/src/libImaging/FliDecode.c
index 6d22c6c4ea8..e21259900e5 100644
--- a/src/libImaging/FliDecode.c
+++ b/src/libImaging/FliDecode.c
@@ -26,7 +26,7 @@
 
 
 int
-ImagingFliDecode(Imaging im, ImagingCodecState state, UINT8* buf, int bytes)
+ImagingFliDecode(Imaging im, ImagingCodecState state, UINT8* buf, Py_ssize_t bytes)
 {
     UINT8* ptr;
     int framesize;
diff --git a/src/libImaging/GifDecode.c b/src/libImaging/GifDecode.c
index 58cf544009b..68429ab26c0 100644
--- a/src/libImaging/GifDecode.c
+++ b/src/libImaging/GifDecode.c
@@ -58,7 +58,7 @@
 
 
 int
-ImagingGifDecode(Imaging im, ImagingCodecState state, UINT8* buffer, int bytes)
+ImagingGifDecode(Imaging im, ImagingCodecState state, UINT8* buffer, Py_ssize_t bytes)
 {
     UINT8* p;
     UINT8* out;
diff --git a/src/libImaging/HexDecode.c b/src/libImaging/HexDecode.c
index 14f5241dc5e..8bd9bf67fa7 100644
--- a/src/libImaging/HexDecode.c
+++ b/src/libImaging/HexDecode.c
@@ -21,7 +21,7 @@
 		(v >= 'A' && v <= 'F') ? v - 'A' + 10 : -1)
 
 int
-ImagingHexDecode(Imaging im, ImagingCodecState state, UINT8* buf, int bytes)
+ImagingHexDecode(Imaging im, ImagingCodecState state, UINT8* buf, Py_ssize_t bytes)
 {
     UINT8* ptr;
     int a, b;
diff --git a/src/libImaging/Imaging.h b/src/libImaging/Imaging.h
index e705e0a604d..25c15e758cf 100644
--- a/src/libImaging/Imaging.h
+++ b/src/libImaging/Imaging.h
@@ -413,22 +413,22 @@ typedef int (*ImagingCodec)(Imaging im, ImagingCodecState state,
                             UINT8* buffer, int bytes);
 
 extern int ImagingBcnDecode(Imaging im, ImagingCodecState state,
-                            UINT8* buffer, int bytes);
+                            UINT8* buffer, Py_ssize_t bytes);
 extern int ImagingBitDecode(Imaging im, ImagingCodecState state,
-                            UINT8* buffer, int bytes);
+                            UINT8* buffer, Py_ssize_t bytes);
 extern int ImagingEpsEncode(Imaging im, ImagingCodecState state,
                             UINT8* buffer, int bytes);
 extern int ImagingFliDecode(Imaging im, ImagingCodecState state,
-                            UINT8* buffer, int bytes);
+                            UINT8* buffer, Py_ssize_t bytes);
 extern int ImagingGifDecode(Imaging im, ImagingCodecState state,
-                            UINT8* buffer, int bytes);
+                            UINT8* buffer, Py_ssize_t bytes);
 extern int ImagingGifEncode(Imaging im, ImagingCodecState state,
                             UINT8* buffer, int bytes);
 extern int ImagingHexDecode(Imaging im, ImagingCodecState state,
-                            UINT8* buffer, int bytes);
+                            UINT8* buffer, Py_ssize_t bytes);
 #ifdef  HAVE_LIBJPEG
 extern int ImagingJpegDecode(Imaging im, ImagingCodecState state,
-                             UINT8* buffer, int bytes);
+                             UINT8* buffer, Py_ssize_t bytes);
 extern int ImagingJpegDecodeCleanup(ImagingCodecState state);
 extern int ImagingJpegUseJCSExtensions(void);
 
@@ -437,7 +437,7 @@ extern int ImagingJpegEncode(Imaging im, ImagingCodecState state,
 #endif
 #ifdef HAVE_OPENJPEG
 extern int ImagingJpeg2KDecode(Imaging im, ImagingCodecState state,
-                               UINT8* buffer, int bytes);
+                               UINT8* buffer, Py_ssize_t bytes);
 extern int ImagingJpeg2KDecodeCleanup(ImagingCodecState state);
 extern int ImagingJpeg2KEncode(Imaging im, ImagingCodecState state,
                                UINT8* buffer, int bytes);
@@ -445,44 +445,44 @@ extern int ImagingJpeg2KEncodeCleanup(ImagingCodecState state);
 #endif
 #ifdef  HAVE_LIBTIFF
 extern int ImagingLibTiffDecode(Imaging im, ImagingCodecState state,
-                                UINT8* buffer, int bytes);
+                                UINT8* buffer, Py_ssize_t bytes);
 extern int ImagingLibTiffEncode(Imaging im, ImagingCodecState state,
                                 UINT8* buffer, int bytes);
 #endif
 #ifdef  HAVE_LIBMPEG
 extern int ImagingMpegDecode(Imaging im, ImagingCodecState state,
-                             UINT8* buffer, int bytes);
+                             UINT8* buffer, Py_ssize_t bytes);
 #endif
 extern int ImagingMspDecode(Imaging im, ImagingCodecState state,
-                            UINT8* buffer, int bytes);
+                            UINT8* buffer, Py_ssize_t bytes);
 extern int ImagingPackbitsDecode(Imaging im, ImagingCodecState state,
-                                 UINT8* buffer, int bytes);
+                                 UINT8* buffer, Py_ssize_t bytes);
 extern int ImagingPcdDecode(Imaging im, ImagingCodecState state,
-                            UINT8* buffer, int bytes);
+                            UINT8* buffer, Py_ssize_t bytes);
 extern int ImagingPcxDecode(Imaging im, ImagingCodecState state,
-                            UINT8* buffer, int bytes);
+                            UINT8* buffer, Py_ssize_t bytes);
 extern int ImagingPcxEncode(Imaging im, ImagingCodecState state,
                             UINT8* buffer, int bytes);
 extern int ImagingRawDecode(Imaging im, ImagingCodecState state,
-                            UINT8* buffer, int bytes);
+                            UINT8* buffer, Py_ssize_t bytes);
 extern int ImagingRawEncode(Imaging im, ImagingCodecState state,
                             UINT8* buffer, int bytes);
 extern int ImagingSgiRleDecode(Imaging im, ImagingCodecState state,
-                               UINT8* buffer, int bytes);
+                               UINT8* buffer, Py_ssize_t bytes);
 extern int ImagingSgiRleDecodeCleanup(ImagingCodecState state);
 extern int ImagingSunRleDecode(Imaging im, ImagingCodecState state,
-                               UINT8* buffer, int bytes);
+                               UINT8* buffer, Py_ssize_t bytes);
 extern int ImagingTgaRleDecode(Imaging im, ImagingCodecState state,
-                               UINT8* buffer, int bytes);
+                               UINT8* buffer, Py_ssize_t bytes);
 extern int ImagingTgaRleEncode(Imaging im, ImagingCodecState state,
                                UINT8* buffer, int bytes);
 extern int ImagingXbmDecode(Imaging im, ImagingCodecState state,
-                            UINT8* buffer, int bytes);
+                            UINT8* buffer, Py_ssize_t bytes);
 extern int ImagingXbmEncode(Imaging im, ImagingCodecState state,
                             UINT8* buffer, int bytes);
 #ifdef  HAVE_LIBZ
 extern int ImagingZipDecode(Imaging im, ImagingCodecState state,
-                            UINT8* buffer, int bytes);
+                            UINT8* buffer, Py_ssize_t bytes);
 extern int ImagingZipDecodeCleanup(ImagingCodecState state);
 extern int ImagingZipEncode(Imaging im, ImagingCodecState state,
                             UINT8* buffer, int bytes);
diff --git a/src/libImaging/Jpeg2KDecode.c b/src/libImaging/Jpeg2KDecode.c
index 9140e007415..f2e437dda28 100644
--- a/src/libImaging/Jpeg2KDecode.c
+++ b/src/libImaging/Jpeg2KDecode.c
@@ -769,7 +769,7 @@ j2k_decode_entry(Imaging im, ImagingCodecState state)
 }
 
 int
-ImagingJpeg2KDecode(Imaging im, ImagingCodecState state, UINT8* buf, int bytes)
+ImagingJpeg2KDecode(Imaging im, ImagingCodecState state, UINT8* buf, Py_ssize_t bytes)
 {
 
     if (bytes){
diff --git a/src/libImaging/JpegDecode.c b/src/libImaging/JpegDecode.c
index 33cc5d0955b..39d96de531b 100644
--- a/src/libImaging/JpegDecode.c
+++ b/src/libImaging/JpegDecode.c
@@ -144,7 +144,7 @@ output(j_common_ptr cinfo)
 /* -------------------------------------------------------------------- */
 
 int
-ImagingJpegDecode(Imaging im, ImagingCodecState state, UINT8* buf, int bytes)
+ImagingJpegDecode(Imaging im, ImagingCodecState state, UINT8* buf, Py_ssize_t bytes)
 {
     JPEGSTATE* context = (JPEGSTATE*) state->context;
     int ok;
diff --git a/src/libImaging/PackDecode.c b/src/libImaging/PackDecode.c
index aea8f04e301..ef54f3c9a4f 100644
--- a/src/libImaging/PackDecode.c
+++ b/src/libImaging/PackDecode.c
@@ -18,7 +18,7 @@
 
 int
 ImagingPackbitsDecode(Imaging im, ImagingCodecState state,
-		      UINT8* buf, int bytes)
+		      UINT8* buf, Py_ssize_t bytes)
 {
     UINT8 n;
     UINT8* ptr;
diff --git a/src/libImaging/PcdDecode.c b/src/libImaging/PcdDecode.c
index f9234389023..8ff264edfc8 100644
--- a/src/libImaging/PcdDecode.c
+++ b/src/libImaging/PcdDecode.c
@@ -24,7 +24,7 @@
 
 
 int
-ImagingPcdDecode(Imaging im, ImagingCodecState state, UINT8* buf, int bytes)
+ImagingPcdDecode(Imaging im, ImagingCodecState state, UINT8* buf, Py_ssize_t bytes)
 {
     int x;
     int chunk;
diff --git a/src/libImaging/PcxDecode.c b/src/libImaging/PcxDecode.c
index e5417f1bdd0..4a5931bee73 100644
--- a/src/libImaging/PcxDecode.c
+++ b/src/libImaging/PcxDecode.c
@@ -17,7 +17,7 @@
 #include "Imaging.h"
 
 int
-ImagingPcxDecode(Imaging im, ImagingCodecState state, UINT8* buf, int bytes)
+ImagingPcxDecode(Imaging im, ImagingCodecState state, UINT8* buf, Py_ssize_t bytes)
 {
     UINT8 n;
     UINT8* ptr;
diff --git a/src/libImaging/RawDecode.c b/src/libImaging/RawDecode.c
index 40c0cb79a41..774d4245b85 100644
--- a/src/libImaging/RawDecode.c
+++ b/src/libImaging/RawDecode.c
@@ -20,7 +20,7 @@
 
 
 int
-ImagingRawDecode(Imaging im, ImagingCodecState state, UINT8* buf, int bytes)
+ImagingRawDecode(Imaging im, ImagingCodecState state, UINT8* buf, Py_ssize_t bytes)
 {
     enum { LINE = 1, SKIP };
     RAWSTATE* rawstate = state->context;
diff --git a/src/libImaging/SgiRleDecode.c b/src/libImaging/SgiRleDecode.c
index 9d8e56376ce..f87c473e3cd 100644
--- a/src/libImaging/SgiRleDecode.c
+++ b/src/libImaging/SgiRleDecode.c
@@ -90,7 +90,7 @@ static int expandrow2(UINT16* dest, UINT16* src, int n, int z)
 
 int
 ImagingSgiRleDecode(Imaging im, ImagingCodecState state,
-		    UINT8* buf, int bytes)
+		    UINT8* buf, Py_ssize_t bytes)
 {
     UINT8 *ptr;
     SGISTATE *c;
diff --git a/src/libImaging/SunRleDecode.c b/src/libImaging/SunRleDecode.c
index 50d816e387f..e627c2c9a28 100644
--- a/src/libImaging/SunRleDecode.c
+++ b/src/libImaging/SunRleDecode.c
@@ -20,7 +20,7 @@
 
 
 int
-ImagingSunRleDecode(Imaging im, ImagingCodecState state, UINT8* buf, int bytes)
+ImagingSunRleDecode(Imaging im, ImagingCodecState state, UINT8* buf, Py_ssize_t bytes)
 {
     int n;
     UINT8* ptr;
diff --git a/src/libImaging/TgaRleDecode.c b/src/libImaging/TgaRleDecode.c
index cad6bc3bcfe..d1971e54623 100644
--- a/src/libImaging/TgaRleDecode.c
+++ b/src/libImaging/TgaRleDecode.c
@@ -20,7 +20,7 @@
 
 int
 ImagingTgaRleDecode(Imaging im, ImagingCodecState state,
-		    UINT8* buf, int bytes)
+		    UINT8* buf, Py_ssize_t bytes)
 {
     int n, depth;
     UINT8* ptr;
diff --git a/src/libImaging/TiffDecode.c b/src/libImaging/TiffDecode.c
index 381f795e01d..a68f73993ff 100644
--- a/src/libImaging/TiffDecode.c
+++ b/src/libImaging/TiffDecode.c
@@ -275,7 +275,7 @@ int ReadStrip(TIFF* tiff, UINT32 row, UINT32* buffer) {
     return 0;
 }
 
-int ImagingLibTiffDecode(Imaging im, ImagingCodecState state, UINT8* buffer, int bytes) {
+int ImagingLibTiffDecode(Imaging im, ImagingCodecState state, UINT8* buffer, Py_ssize_t bytes) {
     TIFFSTATE *clientstate = (TIFFSTATE *)state->context;
     char *filename = "tempfile.tif";
     char *mode = "r";
diff --git a/src/libImaging/XbmDecode.c b/src/libImaging/XbmDecode.c
index 8a203841bef..75b4961abaa 100644
--- a/src/libImaging/XbmDecode.c
+++ b/src/libImaging/XbmDecode.c
@@ -21,7 +21,7 @@
 		(v >= 'A' && v <= 'F') ? v - 'A' + 10 : 0)
 
 int
-ImagingXbmDecode(Imaging im, ImagingCodecState state, UINT8* buf, int bytes)
+ImagingXbmDecode(Imaging im, ImagingCodecState state, UINT8* buf, Py_ssize_t bytes)
 {
     enum { BYTE = 1, SKIP };
 
diff --git a/src/libImaging/ZipDecode.c b/src/libImaging/ZipDecode.c
index e96e3200c14..43601c38eeb 100644
--- a/src/libImaging/ZipDecode.c
+++ b/src/libImaging/ZipDecode.c
@@ -41,7 +41,7 @@ static int get_row_len(ImagingCodecState state, int pass)
 /* -------------------------------------------------------------------- */
 
 int
-ImagingZipDecode(Imaging im, ImagingCodecState state, UINT8* buf, int bytes)
+ImagingZipDecode(Imaging im, ImagingCodecState state, UINT8* buf, Py_ssize_t bytes)
 {
     ZIPSTATE* context = (ZIPSTATE*) state->context;
     int err;