diff --git a/BeefLibs/corlib/src/Array.bf b/BeefLibs/corlib/src/Array.bf
index 89c44b7e..d6e8b8cf 100644
--- a/BeefLibs/corlib/src/Array.bf
+++ b/BeefLibs/corlib/src/Array.bf
@@ -260,6 +260,35 @@ namespace System
 			}
 		}
 
+		public ref T this[Index index]
+		{
+			[Checked, Inline]
+			get
+			{
+				int idx;
+				switch (index)
+				{
+				case .FromFront(let offset): idx = offset;
+				case .FromEnd(let offset): idx = mLength - 1 - offset;
+				}
+				if ((uint)idx >= (uint)mLength)
+					Internal.ThrowIndexOutOfRange(1);
+				return ref (&mFirstElement)[idx];
+			}
+
+			[Unchecked, Inline]
+			get
+			{
+				int idx;
+				switch (index)
+				{
+				case .FromFront(let offset): idx = offset;
+				case .FromEnd(let offset): idx = mLength - 1 - offset;
+				}
+				return ref (&mFirstElement)[idx];
+			}
+		}
+
 		public Span<T> this[IndexRange range]
 		{
 #if !DEBUG
diff --git a/BeefLibs/corlib/src/Collections/List.bf b/BeefLibs/corlib/src/Collections/List.bf
index 9bbb7e7f..a53a3a20 100644
--- a/BeefLibs/corlib/src/Collections/List.bf
+++ b/BeefLibs/corlib/src/Collections/List.bf
@@ -211,6 +211,65 @@ namespace System.Collections
 			}
 		}
 
+		public ref T this[Index index]
+		{
+			[Checked]
+			get
+			{
+				int idx;
+				switch (index)
+				{
+				case .FromFront(let offset): idx = offset;
+				case .FromEnd(let offset): idx = mSize - 1 - offset;
+				}
+				Runtime.Assert((uint)idx < (uint)mSize);
+				return ref mItems[idx];
+			}
+
+			[Unchecked, Inline]
+			get
+			{
+				int idx;
+				switch (index)
+				{
+				case .FromFront(let offset): idx = offset;
+				case .FromEnd(let offset): idx = mSize - 1 - offset;
+				}
+				return ref mItems[idx];
+			}
+
+			[Checked]
+			set
+			{
+				int idx;
+				switch (index)
+				{
+				case .FromFront(let offset): idx = offset;
+				case .FromEnd(let offset): idx = mSize - 1 - offset;
+				}
+				Runtime.Assert((uint)idx < (uint)mSize);
+				mItems[idx] = value;
+#if VERSION_LIST
+				mVersion++;
+#endif
+			}
+
+			[Unchecked, Inline]
+			set
+			{
+				int idx;
+				switch (index)
+				{
+				case .FromFront(let offset): idx = offset;
+				case .FromEnd(let offset): idx = mSize - 1 - offset;
+				}
+				mItems[idx] = value;
+#if VERSION_LIST
+				mVersion++;
+#endif
+			}
+		}
+
 		public Span<T> this[IndexRange range]
 		{
 #if !DEBUG
diff --git a/BeefLibs/corlib/src/Span.bf b/BeefLibs/corlib/src/Span.bf
index f4c971df..88e70617 100644
--- a/BeefLibs/corlib/src/Span.bf
+++ b/BeefLibs/corlib/src/Span.bf
@@ -127,13 +127,48 @@ namespace System
 		
 		public ref T this[int index]
 	    {
-	    	[Inline]
+	    	[Checked]
 	        get
+			{
+				Runtime.Assert((uint)index < (uint)mLength);
+				return ref mPtr[index];
+			}
+
+			[Unchecked, Inline]
+			get
 			{
 				return ref mPtr[index];
 			}
 	    }
 
+		public ref T this[Index index]
+		{
+			[Checked]
+		    get
+			{
+				int idx;
+				switch (index)
+				{
+				case .FromFront(let offset): idx = offset;
+				case .FromEnd(let offset): idx = mLength - 1 - offset;
+				}
+				Runtime.Assert((uint)idx < (uint)mLength);
+				return ref mPtr[idx];
+			}
+
+			[Unchecked, Inline]
+			get
+			{
+				int idx;
+				switch (index)
+				{
+				case .FromFront(let offset): idx = offset;
+				case .FromEnd(let offset): idx = mLength - 1 - offset;
+				}
+				return ref mPtr[idx];
+			}
+		}
+
 		public Span<T> this[IndexRange range]
 		{
 #if !DEBUG