diff --git a/PacketDotNet/RtcpPacket.cs b/PacketDotNet/RtcpPacket.cs
index b7ed9fa2..270e9854 100644
--- a/PacketDotNet/RtcpPacket.cs
+++ b/PacketDotNet/RtcpPacket.cs
@@ -117,7 +117,7 @@ public bool HasPadding
         public int ReceptionReportCount
         {
             get => (Header.Bytes[Header.Offset] & RtcpFields.ReceptionReportCountMask);
-            set => Header.Bytes[Header.Offset] |= (byte) (value & RtcpFields.ReceptionReportCountMask);
+            set => Header.Bytes[Header.Offset] = (byte) ((Header.Bytes[Header.Offset] & ~RtcpFields.ReceptionReportCountMask) | (value & RtcpFields.ReceptionReportCountMask));
         }
 
         /// <summary>
diff --git a/PacketDotNet/RtpPacket.cs b/PacketDotNet/RtpPacket.cs
index df896aaa..37c8adcf 100644
--- a/PacketDotNet/RtpPacket.cs
+++ b/PacketDotNet/RtpPacket.cs
@@ -141,7 +141,7 @@ public int CsrcCount
             get => Header.Bytes[Header.Offset] & RtpFields.CsrcCountMask;
             set
             {
-                Header.Bytes[Header.Offset] |= (byte) (value & RtpFields.CsrcCountMask);
+                Header.Bytes[Header.Offset] = (byte) ((Header.Bytes[Header.Offset] & ~RtpFields.CsrcCountMask) | (value & RtpFields.CsrcCountMask));
                 Header.Length = RtpFields.HeaderLength + CsrcCount * RtpFields.CsrcIdLength;
                 if (HasExtension)
                     Header.Length += RtpFields.ProfileSpecificExtensionHeaderLength + RtpFields.ExtensionLengthLength +
@@ -174,7 +174,7 @@ public bool Marker
         public int PayloadType
         {
             get => Header.Bytes[Header.Offset + 1] & RtpFields.PayloadTypeMask;
-            set => Header.Bytes[Header.Offset + 1] |= (byte) (value & RtpFields.PayloadTypeMask);
+            set => Header.Bytes[Header.Offset + 1] = (byte) ((Header.Bytes[Header.Offset + 1] & ~RtpFields.PayloadTypeMask) | (value & RtpFields.PayloadTypeMask));
         }
 
         /// <summary>