diff --git a/fs_uae_wrapper/base.py b/fs_uae_wrapper/base.py
index d89e496..a4323ed 100644
--- a/fs_uae_wrapper/base.py
+++ b/fs_uae_wrapper/base.py
@@ -219,7 +219,11 @@ class Base(object):
                 changed_options[key] = abspath
                 continue
 
-            changed_options[key] = os.path.abspath(val)
+            _val = os.path.abspath(val)
+            if os.path.exists(_val):
+                changed_options[key] = _val
+            else:
+                changed_options[key] = val
 
         self.fsuae_options.update(changed_options)
 
diff --git a/fs_uae_wrapper/utils.py b/fs_uae_wrapper/utils.py
index 583687f..1e19dbc 100644
--- a/fs_uae_wrapper/utils.py
+++ b/fs_uae_wrapper/utils.py
@@ -144,6 +144,7 @@ def interpolate_variables(string, config_path, base=None):
         - $BASE
     """
 
+    _string = string
     if '$CONFIG' in string:
         conf_path = os.path.dirname(os.path.abspath(config_path))
         string = os.path.abspath(string.replace('$CONFIG', conf_path))
@@ -166,7 +167,9 @@ def interpolate_variables(string, config_path, base=None):
         if '$BASE' in string:
             string = string.replace('$BASE', base)
 
-    return string
+    if os.path.exists(string):
+        return string
+    return _string
 
 
 def get_config(conf_file):