diff --git a/src/Lucene.Net.Tests.Facet/Taxonomy/WriterCache/TestCharBlockArray.cs b/src/Lucene.Net.Tests.Facet/Taxonomy/WriterCache/TestCharBlockArray.cs
index 8b2c667714..b30010a64c 100644
--- a/src/Lucene.Net.Tests.Facet/Taxonomy/WriterCache/TestCharBlockArray.cs
+++ b/src/Lucene.Net.Tests.Facet/Taxonomy/WriterCache/TestCharBlockArray.cs
@@ -44,9 +44,9 @@ public virtual void TestArray()
             // CharsetDecoder decoder = StandardCharsets.UTF_8.newDecoder()
             //     .onUnmappableCharacter(CodingErrorAction.REPLACE)
             //     .onMalformedInput(CodingErrorAction.REPLACE);
-            // 
-            // Encoding decoder = Encoding.GetEncoding(Encoding.UTF8.CodePage, 
-            //     new EncoderReplacementFallback("?"), 
+            //
+            // Encoding decoder = Encoding.GetEncoding(Encoding.UTF8.CodePage,
+            //     new EncoderReplacementFallback("?"),
             //     new DecoderReplacementFallback("?"));
 
             for (int i = 0; i < n; i++)
@@ -247,6 +247,11 @@ public virtual void TestAppendableInterface()
             expected = t.ToString();
             t.Append((char[])null); // No-op
             Assert.AreEqual(expected, t.ToString());
+
+            // LUCENENET specific - test ReadOnlySpan<char> overload
+            t = new CharBlockArray();
+            t.Append("12345678".AsSpan());
+            Assert.AreEqual("12345678", t.ToString());
         }
 
         // LUCENENET: Borrowed this test from TestCharTermAttributeImpl
@@ -285,6 +290,11 @@ public virtual void TestAppendableInterfaceWithLongSequences()
             const string longTestString = "012345678901234567890123456789";
             t.Append(new CharSequenceAnonymousClass(longTestString));
             Assert.AreEqual("4567890123456" + longTestString, t.ToString());
+
+            // LUCENENET specific - test ReadOnlySpan<char> overload
+            t = new CharBlockArray();
+            t.Append("01234567890123456789012345678901234567890123456789".AsSpan());
+            Assert.AreEqual("01234567890123456789012345678901234567890123456789", t.ToString());
         }
 
         private sealed class CharSequenceAnonymousClass : ICharSequence
@@ -319,4 +329,4 @@ public override string ToString()
             }
         }
     }
-}
\ No newline at end of file
+}
diff --git a/src/Lucene.Net.Tests/Analysis/TokenAttributes/TestCharTermAttributeImpl.cs b/src/Lucene.Net.Tests/Analysis/TokenAttributes/TestCharTermAttributeImpl.cs
index cd0b951c9e..6580a3dd23 100644
--- a/src/Lucene.Net.Tests/Analysis/TokenAttributes/TestCharTermAttributeImpl.cs
+++ b/src/Lucene.Net.Tests/Analysis/TokenAttributes/TestCharTermAttributeImpl.cs
@@ -305,6 +305,10 @@ public virtual void TestAppendableInterface()
             expected = t.ToString();
             t.Append((char[])null); // No-op
             Assert.AreEqual(expected, t.ToString());
+
+            // LUCENENET specific - test ReadOnlySpan<char> overload
+            t.SetEmpty().Append("12345678".AsSpan());
+            Assert.AreEqual("12345678", t.ToString());
         }
 
         [Test]
@@ -341,6 +345,10 @@ public virtual void TestAppendableInterfaceWithLongSequences()
             const string longTestString = "012345678901234567890123456789";
             t.Append(new CharSequenceAnonymousClass(this, longTestString));
             Assert.AreEqual("4567890123456" + longTestString, t.ToString());
+
+            // LUCENENET specific - test ReadOnlySpan<char> overload
+            t.SetEmpty().Append("01234567890123456789012345678901234567890123456789".AsSpan());
+            Assert.AreEqual("01234567890123456789012345678901234567890123456789", t.ToString());
         }
 
         private sealed class CharSequenceAnonymousClass : ICharSequence
@@ -479,4 +487,4 @@ public void testAppendPerf() {
 
         */
     }
-}
\ No newline at end of file
+}