diff --git a/RELEASE-NOTES.md b/RELEASE-NOTES.md
index 7fae983d2..5b7090c00 100644
--- a/RELEASE-NOTES.md
+++ b/RELEASE-NOTES.md
@@ -33,6 +33,7 @@ Template for new versions:
 
 * Thanks to new IME support with SDL2, `IClyde.TextInputStart()` and `IClyde.TextInputStop()` must now be appropriately called to start/stop receiving text input when focusing/unfocusing a UI control. This restriction is applied even on the (default) GLFW backend, to enforce consistent usage of these APIs.
 * `[GUI]TextEventArgs` have been renamed to `[GUI]TextEnteredEventArgs`, turned into records, and made to carry a `string` rather than a single text `Rune`.
+* IoC and `DependencyCollection` `Register` methods now have a `TInterface : class` constraint.
 
 ### New features
 
diff --git a/Robust.Shared/IoC/DependencyCollection.cs b/Robust.Shared/IoC/DependencyCollection.cs
index 6e9360507..4d6dfbeb0 100644
--- a/Robust.Shared/IoC/DependencyCollection.cs
+++ b/Robust.Shared/IoC/DependencyCollection.cs
@@ -87,6 +87,7 @@ namespace Robust.Shared.IoC
         /// <inheritdoc />
         public void Register<TInterface, TImplementation>(bool overwrite = false)
             where TImplementation : class, TInterface
+            where TInterface : class
         {
             Register<TInterface, TImplementation>(() =>
             {
@@ -126,6 +127,8 @@ namespace Robust.Shared.IoC
         /// <inheritdoc />
         public void Register<TInterface, TImplementation>(DependencyFactoryDelegate<TImplementation> factory, bool overwrite = false)
             where TImplementation : class, TInterface
+            where TInterface : class
+
         {
             var interfaceType = typeof(TInterface);
             CheckRegisterInterface(interfaceType, typeof(TImplementation), overwrite);
@@ -206,6 +209,7 @@ namespace Robust.Shared.IoC
 
         /// <inheritdoc />
         public void RegisterInstance<TInterface>(object implementation, bool overwrite = false, bool deferInject = false)
+            where TInterface : class
         {
             RegisterInstance(typeof(TInterface), implementation, overwrite, deferInject);
         }
diff --git a/Robust.Shared/IoC/IDependencyCollection.cs b/Robust.Shared/IoC/IDependencyCollection.cs
index ac2e277f0..a28c91f3c 100644
--- a/Robust.Shared/IoC/IDependencyCollection.cs
+++ b/Robust.Shared/IoC/IDependencyCollection.cs
@@ -50,7 +50,8 @@ namespace Robust.Shared.IoC
         /// or if an already instantiated interface (by <see cref="DependencyCollection.BuildGraph"/>) is attempting to be overwritten.
         /// </exception>
         void Register<TInterface, [MeansImplicitUse] TImplementation>(bool overwrite = false)
-            where TImplementation : class, TInterface;
+            where TImplementation : class, TInterface
+            where TInterface : class;
 
         /// <summary>
         /// Registers an interface to an implementation, to make it accessible to <see cref="DependencyCollection.Resolve{T}"/>
@@ -68,7 +69,8 @@ namespace Robust.Shared.IoC
         /// or if an already instantiated interface (by <see cref="DependencyCollection.BuildGraph"/>) is attempting to be overwritten.
         /// </exception>
         void Register<TInterface, TImplementation>(DependencyFactoryDelegate<TImplementation> factory, bool overwrite = false)
-            where TImplementation : class, TInterface;
+            where TImplementation : class, TInterface
+            where TInterface : class;
 
 
         /// <summary>
@@ -113,7 +115,8 @@ namespace Robust.Shared.IoC
         ///     If this is false, dependencies will be immediately injected. If the registered type requires dependencies
         ///     that don't exist yet because you have not called BuildGraph, set this to true.
         /// </param>
-        void RegisterInstance<TInterface>(object implementation, bool overwrite = false, bool deferInject = false);
+        void RegisterInstance<TInterface>(object implementation, bool overwrite = false, bool deferInject = false)
+            where TInterface : class;
 
         /// <summary>
         ///     Registers an interface to an existing instance of an implementation,
diff --git a/Robust.Shared/IoC/IoCManager.cs b/Robust.Shared/IoC/IoCManager.cs
index 17aa48078..48d2e597b 100644
--- a/Robust.Shared/IoC/IoCManager.cs
+++ b/Robust.Shared/IoC/IoCManager.cs
@@ -101,6 +101,7 @@ namespace Robust.Shared.IoC
         /// </exception>
         public static void Register<TInterface, [MeansImplicitUse] TImplementation>(bool overwrite = false)
             where TImplementation : class, TInterface
+            where TInterface : class
         {
             DebugTools.Assert(_container.IsValueCreated, NoContextAssert);
 
@@ -141,6 +142,7 @@ namespace Robust.Shared.IoC
         /// </exception>
         public static void Register<TInterface, TImplementation>(DependencyFactoryDelegate<TImplementation> factory, bool overwrite = false)
             where TImplementation : class, TInterface
+            where TInterface : class
         {
             DebugTools.Assert(_container.IsValueCreated, NoContextAssert);
 
@@ -166,6 +168,7 @@ namespace Robust.Shared.IoC
         ///     that don't exist yet because you have not called BuildGraph, set this to true.
         /// </param>
         public static void RegisterInstance<TInterface>(object implementation, bool overwrite = false, bool deferInject = false)
+            where TInterface : class
         {
             DebugTools.Assert(_container.IsValueCreated, NoContextAssert);