diff --git a/doc/index/Doxyfile b/doc/index/Doxyfile
index 597de34d0..9e73dedbc 100644
--- a/doc/index/Doxyfile
+++ b/doc/index/Doxyfile
@@ -52,7 +52,6 @@ SUBGROUPING            = YES
 INLINE_GROUPED_CLASSES = NO
 INLINE_SIMPLE_STRUCTS  = NO
 TYPEDEF_HIDES_STRUCT   = NO
-SYMBOL_CACHE_SIZE      = 0
 LOOKUP_CACHE_SIZE      = 0
 #---------------------------------------------------------------------------
 # Build related configuration options