diff --git a/CMakeLists.txt b/CMakeLists.txt
index 17ddf6b..7fe1e6b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -118,7 +118,7 @@ else (USE_EXT_GD)
 	endif (ENABLE_ICONV)
 
 	IF (ENABLE_WEBP)
-		FIND_PACKAGE(WEBP REQUIRED)
+		FIND_PACKAGE(WebP CONFIG REQUIRED)
 	ENDIF (ENABLE_WEBP)
 
 	IF (ENABLE_HEIF)
diff --git a/src/config.h.cmake b/src/config.h.cmake
index 2b46a17..af98d23 100644
--- a/src/config.h.cmake
+++ b/src/config.h.cmake
@@ -139,3 +139,8 @@
 
 /* Version number of package */
 #cmakedefine VERSION
+
+#ifdef _MSC_VER
+    #define ssize_t SSIZE_T
+    #define SSIZE_MAX MAXSSIZE_T
+#endif
\ No newline at end of file
diff --git a/src/gd_intern.h b/src/gd_intern.h
index f8f3b5d..380f4db 100644
--- a/src/gd_intern.h
+++ b/src/gd_intern.h
@@ -29,6 +29,14 @@
 # endif
 #endif
 
+#ifdef _MSC_VER
+#define  ssize_t SSIZE_T
+#define MAXSIZE_T ((SIZE_T)~ ((SIZE_T)0))
+#define MAXSSIZE_T ((SSIZE_T) (MAXSIZE_T >> 1))
+#define MINSSIZE_T ((SSIZE_T)~MAXSSIZE_T)
+#define SSIZE_MAX MAXSSIZE_T
+#endif
+
 #include "gd.h"
 
 #define MIN(a,b) ((a)<(b)?(a):(b))
diff --git a/src/getopt.c b/src/getopt.c
index 8651b87..00bccde 100644
--- a/src/getopt.c
+++ b/src/getopt.c
@@ -33,7 +33,10 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+
+#ifndef _WIN32
 #include <unistd.h>
+#endif
 
 int	opterr = 1,		/* if error message should be printed */
 	optind = 1,		/* index into parent argv vector */