--- a/AppRun.c
+++ b/AppRun.c
@@ -156,6 +156,7 @@
     char *old_env;
     const int length = 2047;
     char new_env[8][length+1];
+    checkrt(usr_in_appdir);
 
     /* https://docs.python.org/2/using/cmdline.html#envvar-PYTHONHOME */
     snprintf(new_env[0], length, "PYTHONHOME=%s/usr/", appdir);
@@ -164,7 +165,7 @@
     snprintf(new_env[1], length, "PATH=%s/usr/bin/:%s/usr/sbin/:%s/usr/games/:%s/bin/:%s/sbin/:%s", appdir, appdir, appdir, appdir, appdir, old_env);
 
     old_env = getenv("LD_LIBRARY_PATH") ?: "";
-    snprintf(new_env[2], length, "LD_LIBRARY_PATH=%s/usr/lib/:%s/usr/lib/i386-linux-gnu/:%s/usr/lib/x86_64-linux-gnu/:%s/usr/lib32/:%s/usr/lib64/:%s/lib/:%s/lib/i386-linux-gnu/:%s/lib/x86_64-linux-gnu/:%s/lib32/:%s/lib64/:%s", appdir, appdir, appdir, appdir, appdir, appdir, appdir, appdir, appdir, appdir, old_env);
+    snprintf(new_env[2], length, "LD_LIBRARY_PATH=%s%s/usr/lib/:%s/usr/lib/i386-linux-gnu/:%s/usr/lib/x86_64-linux-gnu/:%s/usr/lib32/:%s/usr/lib64/:%s/lib/:%s/lib/i386-linux-gnu/:%s/lib/x86_64-linux-gnu/:%s/lib32/:%s/lib64/:%s", optional, appdir, appdir, appdir, appdir, appdir, appdir, appdir, appdir, appdir, appdir, old_env);
 
     old_env = getenv("PYTHONPATH") ?: "";
     snprintf(new_env[3], length, "PYTHONPATH=%s/usr/share/pyshared/:%s", appdir, old_env);