diff --git a/src/ansi-c/ansi_c_internal_additions.cpp b/src/ansi-c/ansi_c_internal_additions.cpp
index b41c436d0da..6e93a559eef 100644
--- a/src/ansi-c/ansi_c_internal_additions.cpp
+++ b/src/ansi-c/ansi_c_internal_additions.cpp
@@ -281,7 +281,7 @@ void ansi_c_internal_additions(std::string &code)
     if(config.ansi_c.long_int_width>=64)
     {
       code+="typedef signed __int128 __int128_t;\n"
-            "typedef signed __int128 __uint128_t;\n";
+            "typedef unsigned __int128 __uint128_t;\n";
     }
   }