diff --git a/src/lexer.l b/src/lexer.l
index 6c1e70b..c564f80 100644
--- a/src/lexer.l
+++ b/src/lexer.l
@@ -221,7 +221,7 @@ static YY_BUFFER_STATE string_scan_state = 0;
 }
 
 <<EOF>> {
-             if( string_scan_state != 0 || cfg_include_stack_ptr <= 0 )
+             if( cfg_include_stack_ptr <= 0 )
                  {
                  return EOF;
                  }
@@ -336,7 +336,8 @@ void cfg_scan_string_end(void)
     /* restore to previous state
      */
     yy_delete_buffer(string_scan_state);
-    yy_switch_to_buffer(pre_string_scan_state);
+    if (pre_string_scan_state)
+        yy_switch_to_buffer(pre_string_scan_state);
     free(cfg_qstring);
     cfg_qstring = 0;
     qstring_index = qstring_len = 0;