diff --git a/src/common/sdkdefs.h b/src/common/sdkdefs.h
index 5dc3473d..c13ad911 100644
--- a/src/common/sdkdefs.h
+++ b/src/common/sdkdefs.h
@@ -21,6 +21,23 @@ typedef uintptr_t uintp;
 typedef intptr_t intp;
 
 typedef const unsigned char* rsig_t;
+
+// signed size types
 typedef std::make_signed_t<std::size_t> ssize_t;
 
+#ifndef SSIZE_MAX
+#ifdef _WIN64
+#define SSIZE_MAX 9223372036854775807i64
+#define SSIZE_MIN (-9223372036854775807i64 - 1)
+#else
+#define SSIZE_MAX 2147483647
+#define SSIZE_MIN (-2147483647 - 1)
+#endif
+#endif
+
+// unsigned size types
+#ifndef SIZE_MAX
+#define SIZE_MAX ((size_t) -1)
+#endif
+
 #endif // SDKDEFS_H