diff --git a/src/AutoMapper/Configuration/INamingConvention.cs b/src/AutoMapper/Configuration/INamingConvention.cs
index dad9164465..22418c7656 100644
--- a/src/AutoMapper/Configuration/INamingConvention.cs
+++ b/src/AutoMapper/Configuration/INamingConvention.cs
@@ -24,7 +24,9 @@ public string[] Split(string input)
         int lower = 0;
         for (int index = 1; index < input.Length; index++)
         {
-            if (char.IsUpper(input[index]))
+            if (char.IsUpper(input[index]) &&
+                (!char.IsUpper(input[index - 1]) ||
+                 (index + 1 < input.Length && !char.IsUpper(input[index + 1]))))
             {
                 result ??= [];
                 result.Add(input[lower..index]);
diff --git a/src/UnitTests/Bug/NamingConventions.cs b/src/UnitTests/Bug/NamingConventions.cs
index 1344b0c8d8..79d85d9d40 100644
--- a/src/UnitTests/Bug/NamingConventions.cs
+++ b/src/UnitTests/Bug/NamingConventions.cs
@@ -104,6 +104,22 @@ public void Should_map_from_pascal_to_lower()
         _dario.JaSeZovemImenom.ShouldBe("foo");
     }
 }
+public class PascalCaseAcronymInPropertyName : AutoMapperSpecBase
+{
+    class Source { public Inner Form { get; set; } }
+    class Inner { public int XML { get; set; } }
+    class Dest { public int FormXML { get; set; } }
+
+    protected override MapperConfiguration CreateConfiguration() => new(cfg =>
+        cfg.CreateMap<Source, Dest>());
+
+    [Fact]
+    public void Should_flatten_acronym_property()
+    {
+        var result = Mapper.Map<Dest>(new Source { Form = new Inner { XML = 42 } });
+        result.FormXML.ShouldBe(42);
+    }
+}
 
 public class When_mapping_with_lowercase_naming_conventions_two_ways : AutoMapperSpecBase
 {