diff --git a/src/json.hpp b/src/json.hpp
index 3c6063664..9b292f1f0 100644
--- a/src/json.hpp
+++ b/src/json.hpp
@@ -36,6 +36,11 @@
     #endif
 #endif
 
+// enable ssize_t for MSVC
+#ifdef _MSC_VER
+    using ssize_t = SSIZE_T;
+#endif
+
 /*!
 @brief namespace for Niels Lohmann
 @see https://github.com/nlohmann
diff --git a/src/json.hpp.re2c b/src/json.hpp.re2c
index 976c1d80e..666f750da 100644
--- a/src/json.hpp.re2c
+++ b/src/json.hpp.re2c
@@ -36,6 +36,11 @@
     #endif
 #endif
 
+// enable ssize_t for MSVC
+#ifdef _MSC_VER
+    using ssize_t = SSIZE_T;
+#endif
+
 /*!
 @brief namespace for Niels Lohmann
 @see https://github.com/nlohmann