diff --git a/CMakeLists.txt b/CMakeLists.txt
index 35c77d1d..47bd63f5 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -273,7 +273,11 @@ check_type_size("ssize_t" SIZEOF_SSIZE_T)
 if(SIZEOF_SSIZE_T STREQUAL "")
   # ssize_t is a signed type in POSIX storing at least -1.
   # Set it to "int" to match the behavior of AC_TYPE_SSIZE_T (autotools).
-  set(ssize_t int)
+  if(WIN32 AND CMAKE_SIZEOF_VOID_P EQUAL 8)
+    set(ssize_t ptrdiff_t)
+  else()
+    set(ssize_t int)
+  endif()
 endif()
 # AC_TYPE_UINT8_T
 # AC_TYPE_UINT16_T
# https://github.com/nghttp2/nghttp2/pull/1468
diff --git a/lib/nghttp2_buf.c b/lib/nghttp2_buf.c
index 2a435bebf..92f97f7f2 100644
--- a/lib/nghttp2_buf.c
+++ b/lib/nghttp2_buf.c
@@ -82,8 +82,10 @@ void nghttp2_buf_reset(nghttp2_buf *buf) {
 }
 
 void nghttp2_buf_wrap_init(nghttp2_buf *buf, uint8_t *begin, size_t len) {
-  buf->begin = buf->pos = buf->last = buf->mark = begin;
-  buf->end = begin + len;
+  buf->begin = buf->pos = buf->last = buf->mark = buf->end = begin;
+  if (buf->end != NULL) {
+    buf->end += len;
+  }
 }
 
 static int buf_chain_new(nghttp2_buf_chain **chain, size_t chunk_length,
diff --git a/lib/nghttp2_frame.c b/lib/nghttp2_frame.c
index 4821de408..940c723b0 100644
--- a/lib/nghttp2_frame.c
+++ b/lib/nghttp2_frame.c
@@ -818,8 +818,10 @@ int nghttp2_frame_unpack_origin_payload(nghttp2_extension *frame,
   size_t len = 0;
 
   origin = frame->payload;
-  p = payload;
-  end = p + payloadlen;
+  p = end = payload;
+  if (end != NULL) {
+    end += payloadlen;
+  }
 
   for (; p != end;) {
     if (end - p < 2) {
diff --git a/lib/nghttp2_session.c b/lib/nghttp2_session.c
index 563ccd7de..794f141a1 100644
--- a/lib/nghttp2_session.c
+++ b/lib/nghttp2_session.c
@@ -5349,7 +5349,7 @@ static ssize_t inbound_frame_effective_readlen(nghttp2_inbound_frame *iframe,
 
 ssize_t nghttp2_session_mem_recv(nghttp2_session *session, const uint8_t *in,
                                  size_t inlen) {
-  const uint8_t *first = in, *last = in + inlen;
+  const uint8_t *first = in, *last = in;
   nghttp2_inbound_frame *iframe = &session->iframe;
   size_t readlen;
   ssize_t padlen;
@@ -5360,6 +5360,10 @@ ssize_t nghttp2_session_mem_recv(nghttp2_session *session, const uint8_t *in,
   size_t pri_fieldlen;
   nghttp2_mem *mem;
 
+  if (in != NULL) {
+    last += inlen;
+  }
+
   DEBUGF("recv: connection recv_window_size=%d, local_window=%d\n",
          session->recv_window_size, session->local_window_size);
 
@@ -5389,7 +5393,9 @@ ssize_t nghttp2_session_mem_recv(nghttp2_session *session, const uint8_t *in,
       }
 
       iframe->payloadleft -= readlen;
-      in += readlen;
+      if (in != NULL) {
+        in += readlen;
+      }
 
       if (iframe->payloadleft == 0) {
         session_inbound_frame_reset(session);