diff --git a/state.cpp b/state.cpp
index 3c14038..231f6e8 100644
--- a/state.cpp
+++ b/state.cpp
@@ -145,10 +145,10 @@ call_cxx_function_from_c(lutok::cxx_function function,
         lutok::state state = lutok::state_c_gate::connect(raw_state);
         return function(state);
     } catch (const std::exception& e) {
-        std::strncpy(error_buf, e.what(), sizeof(error_buf));
+        std::strncpy(error_buf, e.what(), sizeof(error_buf) - 1);
     } catch (...) {
         std::strncpy(error_buf, "Unhandled exception in Lua C++ hook",
-                     sizeof(error_buf));
+                     sizeof(error_buf) - 1);
     }
     error_buf[sizeof(error_buf) - 1] = '\0';
     // We raise the Lua error from outside the try/catch context and we use