diff --git a/src/main/java/com/fasterxml/jackson/core/json/WriterBasedJsonGenerator.java b/src/main/java/com/fasterxml/jackson/core/json/WriterBasedJsonGenerator.java
index d9d661c4a3..e1e3f72630 100644
--- a/src/main/java/com/fasterxml/jackson/core/json/WriterBasedJsonGenerator.java
+++ b/src/main/java/com/fasterxml/jackson/core/json/WriterBasedJsonGenerator.java
@@ -1821,7 +1821,7 @@ private void _appendCharacterEscape(char ch, int escCode)
             return;
         }
         if (escCode != CharacterEscapes.ESCAPE_CUSTOM) { // std, \\uXXXX
-            if ((_outputTail + 2) > _outputEnd) {
+            if ((_outputTail + 6) > _outputEnd) {
                 _flushBuffer();
             }
             int ptr = _outputTail;