diff --git a/BeefLibs/corlib/src/SizedArray.bf b/BeefLibs/corlib/src/SizedArray.bf
index aef8e972..028f3792 100644
--- a/BeefLibs/corlib/src/SizedArray.bf
+++ b/BeefLibs/corlib/src/SizedArray.bf
@@ -26,7 +26,7 @@ namespace System
 			return .(&val.mVal, CSize);
 		}
 
-		public void SetAll(T value)
+		public void SetAll(T value) mut
 		{
 			for (int i < CSize)
 				mVal[i] = value;