diff --git a/src/libraries/System.Runtime.Numerics/src/System/Numerics/BigInteger.cs b/src/libraries/System.Runtime.Numerics/src/System/Numerics/BigInteger.cs
index e173705da39c47..dced09c94df283 100644
--- a/src/libraries/System.Runtime.Numerics/src/System/Numerics/BigInteger.cs
+++ b/src/libraries/System.Runtime.Numerics/src/System/Numerics/BigInteger.cs
@@ -384,7 +384,7 @@ public BigInteger(ReadOnlySpan<byte> value, bool isUnsigned = false, bool isBigE
                     // The bytes parameter is in little-endian byte order.
                     // We can just copy the bytes directly into the uint array.
 
-                    value.Slice(0, wholeUInt32Count * 4).CopyTo(MemoryMarshal.AsBytes<uint>(val));
+                    value.Slice(0, wholeUInt32Count * 4).CopyTo(MemoryMarshal.AsBytes(val.AsSpan()));
                 }
 
                 // In both of the above cases on big-endian architecture, we need to perform