diff --git a/X10D.Tests/src/Core/ArrayTests.cs b/X10D.Tests/src/Core/ArrayTests.cs
index c837c7e..5549a4d 100644
--- a/X10D.Tests/src/Core/ArrayTests.cs
+++ b/X10D.Tests/src/Core/ArrayTests.cs
@@ -1,4 +1,5 @@
 using Microsoft.VisualStudio.TestTools.UnitTesting;
+using X10D.Core;
 
 namespace X10D.Tests.Core;
 
diff --git a/X10D.Tests/src/Core/EnumerableTests.cs b/X10D.Tests/src/Core/EnumerableTests.cs
index 3e37d55..13fd78a 100644
--- a/X10D.Tests/src/Core/EnumerableTests.cs
+++ b/X10D.Tests/src/Core/EnumerableTests.cs
@@ -1,5 +1,6 @@
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using X10D.Collections;
+using X10D.Core;
 
 namespace X10D.Tests.Core;
 
diff --git a/X10D/src/Extensions/Extensions.cs b/X10D/src/Core/Extensions.cs
similarity index 97%
rename from X10D/src/Extensions/Extensions.cs
rename to X10D/src/Core/Extensions.cs
index d446978..773217f 100644
--- a/X10D/src/Extensions/Extensions.cs
+++ b/X10D/src/Core/Extensions.cs
@@ -1,4 +1,4 @@
-namespace X10D;
+namespace X10D.Core;
 
 /// <summary>
 ///     Extension methods which apply to all types.