diff --git a/src/common/decls.h b/src/common/decls.h
index 2f5bb85a..b8b23a05 100644
--- a/src/common/decls.h
+++ b/src/common/decls.h
@@ -16,4 +16,7 @@ using std::ostringstream;
 using std::unordered_map;
 
 namespace fs = std::filesystem;
-namespace js = rapidjson;
\ No newline at end of file
+namespace js = rapidjson;
+
+// Signed size type
+typedef std::make_signed_t<std::size_t> ssize_t;