diff --git a/test/hbd_metrics_test.cc b/test/hbd_metrics_test.cc
index f8c0517..abe82be 100644
--- a/test/hbd_metrics_test.cc
+++ b/test/hbd_metrics_test.cc
@@ -96,7 +96,7 @@
   void RunAccuracyCheck() {
     const int width = 1920;
     const int height = 1080;
-    int i = 0;
+    size_t i = 0;
     const uint8_t kPixFiller = 128;
     YV12_BUFFER_CONFIG lbd_src, lbd_dst;
     YV12_BUFFER_CONFIG hbd_src, hbd_dst;
diff --git a/vpx_scale/generic/yv12config.c b/vpx_scale/generic/yv12config.c
index 6ed4321..13fbd28 100644
--- a/vpx_scale/generic/yv12config.c
+++ b/vpx_scale/generic/yv12config.c
@@ -99,17 +99,21 @@
       memset(ybf->buffer_alloc, 0, (int)frame_size);
 #endif
 #endif
-    } else if (frame_size > (size_t)ybf->buffer_alloc_sz) {
+    } else if (frame_size > ybf->buffer_alloc_sz) {
       // Allocation to hold larger frame, or first allocation.
       vpx_free(ybf->buffer_alloc);
       ybf->buffer_alloc = NULL;
 
       if (frame_size != (size_t)frame_size) return -1;
 
+      // TODO(yunqingwang): On 32 bit systems, the maximum resolution supported
+      // in the encoder is 4k(3840x2160). The malloc() would fail if encoding
+      // >4k video on a 32 bit system. Later, maybe disable usage of up-sampled
+      // references to allow >4k video encoding on 32 bit platforms.
       ybf->buffer_alloc = (uint8_t *)vpx_memalign(32, (size_t)frame_size);
       if (!ybf->buffer_alloc) return -1;
 
-      ybf->buffer_alloc_sz = (int)frame_size;
+      ybf->buffer_alloc_sz = (size_t)frame_size;
 
       // This memset is needed for fixing valgrind error from C loop filter
       // due to access uninitialized memory in frame border. It could be
@@ -137,7 +141,7 @@
     ybf->uv_stride = uv_stride;
 
     ybf->border = border;
-    ybf->frame_size = (int)frame_size;
+    ybf->frame_size = (size_t)frame_size;
     ybf->subsampling_x = ss_x;
     ybf->subsampling_y = ss_y;
 
diff --git a/vpx_scale/yv12config.h b/vpx_scale/yv12config.h
index 6b72c72..d581db9 100644
--- a/vpx_scale/yv12config.h
+++ b/vpx_scale/yv12config.h
@@ -53,9 +53,9 @@
   uint8_t *alpha_buffer;
 
   uint8_t *buffer_alloc;
-  int buffer_alloc_sz;
+  size_t buffer_alloc_sz;
   int border;
-  int frame_size;
+  size_t frame_size;
   int subsampling_x;
   int subsampling_y;
   unsigned int bit_depth;