diff --git a/lib/Makefile.msvc b/lib/Makefile.msvc
index 2a930d11..2b8f1848 100644
--- a/lib/Makefile.msvc
+++ b/lib/Makefile.msvc
@@ -62,7 +62,7 @@ AR		 := lib
 #LD		 := xilink
 #AR		 := xilib
 RC		 := rc
-CFLAGS   := -I./includes -Dssize_t=long -D_U_=""
+CFLAGS   := -I./includes -Dssize_t=SSIZE_T -D_U_=""
 
 CFLAGS_R := -nologo -MD  -W3 -Z7 -DBUILDING_NGHTTP2
 CFLAGS_D := -nologo -MDd -W3 -Z7 -DBUILDING_NGHTTP2 \
diff --git a/lib/includes/nghttp2/nghttp2.h b/lib/includes/nghttp2/nghttp2.h
index d567afd3..8e87ce4b 100644
--- a/lib/includes/nghttp2/nghttp2.h
+++ b/lib/includes/nghttp2/nghttp2.h
@@ -35,6 +35,17 @@
 extern "C" {
 #endif
 
+/* For Win32 application, use type NGHTTP2_SSIZE_T instead of
+   ssize_t. */
+#if defined(WIN32)
+#pragma once
+#include <basetsd.h>
+typedef SSIZE_T NGHTTP2_SSIZE_T;
+#if !defined(BUILDING_NGHTTP2)
+#define ssize_t NGHTTP2_SSIZE_T
+#endif
+#endif
+
 #include <stdlib.h>
 #if defined(_MSC_VER) && (_MSC_VER < 1800)
 /* MSVC < 2013 does not have inttypes.h because it is not C99
@@ -5003,6 +5014,12 @@ NGHTTP2_EXTERN int32_t nghttp2_stream_get_weight(nghttp2_stream *stream);
 NGHTTP2_EXTERN int32_t
 nghttp2_stream_get_sum_dependency_weight(nghttp2_stream *stream);
 
+#if defined(WIN32)
+#if !defined(BUILDING_NGHTTP2)
+#undef ssize_t
+#endif
+#endif
+
 #ifdef __cplusplus
 }
 #endif