diff --git a/README.md b/README.md
index 30e1872..23c8818 100644
--- a/README.md
+++ b/README.md
@@ -1997,7 +1997,7 @@ var patch = new SomePatchRequestModel {
     Username = "Updated Name"
 
     Operations = new Dictionary<string, PatchOperation> {
-        { "Username", PartchOperation.Replace }
+        { "Username", PartchOperation.SetField }
     }
 };
 
diff --git a/src/MaksIT.Core/Abstractions/Webapi/PatchRequestModelBase.cs b/src/MaksIT.Core/Abstractions/Webapi/PatchRequestModelBase.cs
index 1ff17ca..d3ded78 100644
--- a/src/MaksIT.Core/Abstractions/Webapi/PatchRequestModelBase.cs
+++ b/src/MaksIT.Core/Abstractions/Webapi/PatchRequestModelBase.cs
@@ -23,5 +23,11 @@ public abstract class PatchRequestModelBase : RequestModelBase {
     if (!HasNonNullPatchField) {
       yield return new ValidationResult("At least one patch field must be provided", new string[] { "PatchField" });
     }
+
+    foreach (var operation in Operations) {
+      if (!Enum.IsDefined(typeof(PatchOperation), operation.Value)) {
+        yield return new ValidationResult($"Invalid patch operation '{operation.Value}' for property '{operation.Key}'", new string[] { operation.Key });
+      }
+    }
   }
 }
diff --git a/src/MaksIT.Core/MaksIT.Core.csproj b/src/MaksIT.Core/MaksIT.Core.csproj
index 64ea5c5..d8e068c 100644
--- a/src/MaksIT.Core/MaksIT.Core.csproj
+++ b/src/MaksIT.Core/MaksIT.Core.csproj
@@ -8,7 +8,7 @@
 
     <!-- NuGet package metadata -->
     <PackageId>MaksIT.Core</PackageId>
-    <Version>1.2.3</Version>
+    <Version>1.2.4</Version>
     <Authors>Maksym Sadovnychyy</Authors>
     <Company>MAKS-IT</Company>
     <Product>MaksIT.Core</Product>
diff --git a/src/MaksIT.Core/Webapi/Models/PatchOperation.cs b/src/MaksIT.Core/Webapi/Models/PatchOperation.cs
index cd74a68..a8d7ba0 100644
--- a/src/MaksIT.Core/Webapi/Models/PatchOperation.cs
+++ b/src/MaksIT.Core/Webapi/Models/PatchOperation.cs
@@ -3,22 +3,37 @@
 public enum PatchOperation {
 
   /// <summary>
-  /// When you need to replace some field, or relpace item in collection
+  /// When you need to set or replace a normal field
   /// </summary>
-  Replace,
+  SetField,
 
   /// <summary>
-  /// When you need to set some field, or add item to collection
+  /// When you need to set a normal field to null
   /// </summary>
-  Add,
+  RemoveField,
 
   /// <summary>
-  /// When you need to set some field to null, or remove item from collection
+  /// When you need to add an item to a collection
   /// </summary>
-  Remove,
+  AddToCollection,
 
   /// <summary>
-  /// When you need to clear collection
+  /// When you need to remove an item from a collection
   /// </summary>
-  Clear
+  RemoveFromCollection,
+
+  /// <summary>
+  /// When you need to replace a collection
+  /// </summary>
+  ReplaceCollection,
+
+  /// <summary>
+  /// When you need to clear a collection
+  /// </summary>
+  ClearCollection,
+
+  /// <summary>
+  /// When you need to set a collection to null
+  /// </summary>
+  RemoveCollection
 }