diff --git a/src/engine/engine_io.c b/src/engine/engine_io.c
index 8a8e59b087..a77ac4fa8b 100644
--- a/src/engine/engine_io.c
+++ b/src/engine/engine_io.c
@@ -529,6 +529,9 @@ void mj_saveModel(const mjModel* m, const char* filename, void* buffer, int buff
   }
 
   if (fp) {
+    if (ferror(fp)) {
+      mju_warning("Error writing to file '%s'", filename);
+    }
     fclose(fp);
   }
 }
diff --git a/src/ui/ui_main.c b/src/ui/ui_main.c
index ffc2fca24e..887d870c3a 100644
--- a/src/ui/ui_main.c
+++ b/src/ui/ui_main.c
@@ -1894,7 +1894,7 @@ static void shortcuthelp(mjrRect r, int modifier, int shortcut,
   }
 
   // combine
-  strcat(text, key);
+  mjSTRNCAT(text, key);
 
   // make rectangle for shortcut
   int g_textver = SCL(ui->spacing.textver, con);