diff --git a/src/libraries/Common/src/System/Text/ValueStringBuilder.cs b/src/libraries/Common/src/System/Text/ValueStringBuilder.cs
index 50dc63ad13b744..b89d7e01caf22e 100644
--- a/src/libraries/Common/src/System/Text/ValueStringBuilder.cs
+++ b/src/libraries/Common/src/System/Text/ValueStringBuilder.cs
@@ -170,9 +170,10 @@ public void Insert(int index, string? s)
         public void Append(char c)
         {
             int pos = _pos;
-            if ((uint)pos < (uint)_chars.Length)
+            Span<char> chars = _chars;
+            if ((uint)pos < (uint)chars.Length)
             {
-                _chars[pos] = c;
+                chars[pos] = c;
                 _pos = pos + 1;
             }
             else