diff --git a/SabreTools.Serialization/Deserializers/InstallShieldCabinet.cs b/SabreTools.Serialization/Deserializers/InstallShieldCabinet.cs
index 95d1e17b..9dcfaaf9 100644
--- a/SabreTools.Serialization/Deserializers/InstallShieldCabinet.cs
+++ b/SabreTools.Serialization/Deserializers/InstallShieldCabinet.cs
@@ -36,7 +36,7 @@ namespace SabreTools.Serialization.Deserializers
                 #endregion
 
                 // Get the major version
-                int majorVersion = GetMajorVersion(commonHeader);
+                int majorVersion = commonHeader.GetMajorVersion();
 
                 #region Volume Header
 
@@ -725,30 +725,5 @@ namespace SabreTools.Serialization.Deserializers
 
             return obj;
         }
-
-        #region Helpers
-
-        /// <summary>
-        /// Get the major version of the cabinet
-        /// </summary>
-        /// <remarks>This should live in the wrapper but is needed during parsing</remarks>
-        public static int GetMajorVersion(CommonHeader commonHeader)
-        {
-            uint majorVersion = commonHeader.Version;
-            if (majorVersion >> 24 == 1)
-            {
-                majorVersion = (majorVersion >> 12) & 0x0F;
-            }
-            else if (majorVersion >> 24 == 2 || majorVersion >> 24 == 4)
-            {
-                majorVersion = majorVersion & 0xFFFF;
-                if (majorVersion != 0)
-                    majorVersion /= 100;
-            }
-
-            return (int)majorVersion;
-        }
-
-        #endregion
     }
 }
diff --git a/SabreTools.Serialization/Extensions.InstallShieldCabinet.cs b/SabreTools.Serialization/Extensions.InstallShieldCabinet.cs
new file mode 100644
index 00000000..08d0e091
--- /dev/null
+++ b/SabreTools.Serialization/Extensions.InstallShieldCabinet.cs
@@ -0,0 +1,47 @@
+using SabreTools.Models.InstallShieldCabinet;
+
+namespace SabreTools.Serialization
+{
+    public static partial class Extensions
+    {
+        /// <summary>
+        /// Get the major version of an InstallShield Cabinet
+        /// </summary>
+        /// <param name="cabinet">Cabinet to derive the version from</param>
+        /// <returns>Major version of the cabinet, -1 on error</returns>
+        public static int GetMajorVersion(this Cabinet? cabinet)
+        {
+            // Ignore invalid cabinets
+            if (cabinet == null)
+                return -1;
+
+            return cabinet.CommonHeader.GetMajorVersion();
+        }
+
+        /// <summary>
+        /// Get the major version of an InstallShield Cabinet
+        /// </summary>
+        /// <param name="commonHeader">CommonHeader to derive the version from</param>
+        /// <returns>Major version of the cabinet, -1 on error</returns>
+        public static int GetMajorVersion(this CommonHeader? commonHeader)
+        {
+            // Ignore invalid headers
+            if (commonHeader == null)
+                return -1;
+
+            uint majorVersion = commonHeader.Version;
+            if (majorVersion >> 24 == 1)
+            {
+                majorVersion = (majorVersion >> 12) & 0x0F;
+            }
+            else if (majorVersion >> 24 == 2 || majorVersion >> 24 == 4)
+            {
+                majorVersion &= 0xFFFF;
+                if (majorVersion != 0)
+                    majorVersion /= 100;
+            }
+
+            return (int)majorVersion;
+        }
+    }
+}
\ No newline at end of file
diff --git a/SabreTools.Serialization/Wrappers/InstallShieldCabinet.cs b/SabreTools.Serialization/Wrappers/InstallShieldCabinet.cs
index 1a19f6ad..4bfa9586 100644
--- a/SabreTools.Serialization/Wrappers/InstallShieldCabinet.cs
+++ b/SabreTools.Serialization/Wrappers/InstallShieldCabinet.cs
@@ -64,25 +64,7 @@ namespace SabreTools.Serialization.Wrappers
         /// <summary>
         /// The major version of the cabinet
         /// </summary>
-        public int MajorVersion
-        {
-            get
-            {
-                uint majorVersion = Model.CommonHeader?.Version ?? 0;
-                if (majorVersion >> 24 == 1)
-                {
-                    majorVersion = (majorVersion >> 12) & 0x0F;
-                }
-                else if (majorVersion >> 24 == 2 || majorVersion >> 24 == 4)
-                {
-                    majorVersion = majorVersion & 0xFFFF;
-                    if (majorVersion != 0)
-                        majorVersion /= 100;
-                }
-
-                return (int)majorVersion;
-            }
-        }
+        public int MajorVersion => Model.CommonHeader.GetMajorVersion();
 
         #endregion