diff --git a/src/dec/vp8.c b/src/dec/vp8.c
index 7b0e38ea..ff3c7d1f 100644
--- a/src/dec/vp8.c
+++ b/src/dec/vp8.c
@@ -82,7 +82,7 @@ int VP8SetError(VP8Decoder* const dec,
 
 //------------------------------------------------------------------------------
 
-int VP8GetInfo(const uint8_t* data, uint32_t data_size, uint32_t chunk_size,
+int VP8GetInfo(const uint8_t* data, size_t data_size, size_t chunk_size,
                int* width, int* height) {
   if (data_size < 10) {
     return 0;         // not enough data
@@ -173,7 +173,7 @@ static int ParseSegmentHeader(VP8BitReader* br,
 // is returned, and this is an unrecoverable error.
 // If the partitions were positioned ok, VP8_STATUS_OK is returned.
 static VP8StatusCode ParsePartitions(VP8Decoder* const dec,
-                                     const uint8_t* buf, uint32_t size) {
+                                     const uint8_t* buf, size_t size) {
   VP8BitReader* const br = &dec->br_;
   const uint8_t* sz = buf;
   const uint8_t* buf_end = buf + size;
@@ -244,7 +244,7 @@ static int ParseFilterHeader(VP8BitReader* br, VP8Decoder* const dec) {
 // Topmost call
 int VP8GetHeaders(VP8Decoder* const dec, VP8Io* const io) {
   const uint8_t* buf;
-  uint32_t buf_size;
+  size_t buf_size;
   VP8FrameHeader* frm_hdr;
   VP8PictureHeader* pic_hdr;
   VP8BitReader* br;
diff --git a/src/dec/vp8i.h b/src/dec/vp8i.h
index d3aeb35e..af392d8e 100644
--- a/src/dec/vp8i.h
+++ b/src/dec/vp8i.h
@@ -294,8 +294,8 @@ int VP8SetError(VP8Decoder* const dec,
 // width and height. Returns 0 in case of formatting error. *width/*height
 // can be passed NULL.
 int VP8GetInfo(const uint8_t* data,
-               uint32_t data_size,    // data available so far
-               uint32_t chunk_size,   // total data size expect in the chunk
+               size_t data_size,    // data available so far
+               size_t chunk_size,   // total data size expect in the chunk
                int *width, int *height);
 
 // in tree.c
diff --git a/src/dec/webpi.h b/src/dec/webpi.h
index 3f6172af..7dba85f9 100644
--- a/src/dec/webpi.h
+++ b/src/dec/webpi.h
@@ -59,7 +59,7 @@ void WebPResetDecParams(WebPDecParams* const params);
 // Structure storing a description of the RIFF headers.
 typedef struct {
   const uint8_t* data;         // input buffer
-  uint32_t data_size;          // input buffer size
+  size_t data_size;            // input buffer size
   size_t offset;               // offset to main data chunk (VP8 or VP8L)
   const uint8_t* alpha_data;   // points to alpha chunk (if present)
   uint32_t alpha_data_size;    // alpha chunk size