diff --git a/src/libraries/System.Collections/ref/System.Collections.cs b/src/libraries/System.Collections/ref/System.Collections.cs
index 85f581fb8ad11c..c10810f6a5c97d 100644
--- a/src/libraries/System.Collections/ref/System.Collections.cs
+++ b/src/libraries/System.Collections/ref/System.Collections.cs
@@ -45,11 +45,11 @@ namespace System.Collections.Generic
     public static partial class CollectionExtensions
     {
         [return: System.Diagnostics.CodeAnalysis.MaybeNullAttribute]
-        public static TValue GetValueOrDefault<TKey, TValue>(this System.Collections.Generic.IReadOnlyDictionary<TKey, TValue> dictionary, TKey key) where TKey : notnull { throw null; }
+        public static TValue GetValueOrDefault<TKey, TValue>(this System.Collections.Generic.IReadOnlyDictionary<TKey, TValue> dictionary, TKey key) { throw null; }
         [return: System.Diagnostics.CodeAnalysis.MaybeNullAttribute]
-        public static TValue GetValueOrDefault<TKey, TValue>(this System.Collections.Generic.IReadOnlyDictionary<TKey, TValue> dictionary, TKey key, [System.Diagnostics.CodeAnalysis.AllowNullAttribute] TValue defaultValue) where TKey : notnull { throw null; }
-        public static bool Remove<TKey, TValue>(this System.Collections.Generic.IDictionary<TKey, TValue> dictionary, TKey key, [System.Diagnostics.CodeAnalysis.MaybeNullWhenAttribute(false)] out TValue value) where TKey : notnull { throw null; }
-        public static bool TryAdd<TKey, TValue>(this System.Collections.Generic.IDictionary<TKey, TValue> dictionary, TKey key, TValue value) where TKey : notnull { throw null; }
+        public static TValue GetValueOrDefault<TKey, TValue>(this System.Collections.Generic.IReadOnlyDictionary<TKey, TValue> dictionary, TKey key, [System.Diagnostics.CodeAnalysis.AllowNullAttribute] TValue defaultValue) { throw null; }
+        public static bool Remove<TKey, TValue>(this System.Collections.Generic.IDictionary<TKey, TValue> dictionary, TKey key, [System.Diagnostics.CodeAnalysis.MaybeNullWhenAttribute(false)] out TValue value) { throw null; }
+        public static bool TryAdd<TKey, TValue>(this System.Collections.Generic.IDictionary<TKey, TValue> dictionary, TKey key, TValue value) { throw null; }
     }
     public abstract partial class Comparer<T> : System.Collections.Generic.IComparer<T>, System.Collections.IComparer
     {
diff --git a/src/libraries/System.Collections/src/System/Collections/Generic/CollectionExtensions.cs b/src/libraries/System.Collections/src/System/Collections/Generic/CollectionExtensions.cs
index 24eed76b7e3b2d..a3b0bddcb1f721 100644
--- a/src/libraries/System.Collections/src/System/Collections/Generic/CollectionExtensions.cs
+++ b/src/libraries/System.Collections/src/System/Collections/Generic/CollectionExtensions.cs
@@ -9,13 +9,13 @@ namespace System.Collections.Generic
     public static class CollectionExtensions
     {
         [return: MaybeNull]
-        public static TValue GetValueOrDefault<TKey, TValue>(this IReadOnlyDictionary<TKey, TValue> dictionary, TKey key) where TKey : notnull
+        public static TValue GetValueOrDefault<TKey, TValue>(this IReadOnlyDictionary<TKey, TValue> dictionary, TKey key)
         {
             return dictionary.GetValueOrDefault(key, default);
         }
 
         [return: MaybeNull]
-        public static TValue GetValueOrDefault<TKey, TValue>(this IReadOnlyDictionary<TKey, TValue> dictionary, TKey key, [AllowNull] TValue defaultValue) where TKey : notnull
+        public static TValue GetValueOrDefault<TKey, TValue>(this IReadOnlyDictionary<TKey, TValue> dictionary, TKey key, [AllowNull] TValue defaultValue)
         {
             if (dictionary == null)
             {
@@ -26,7 +26,7 @@ public static TValue GetValueOrDefault<TKey, TValue>(this IReadOnlyDictionary<TK
             return dictionary.TryGetValue(key, out value) ? value : defaultValue;
         }
 
-        public static bool TryAdd<TKey, TValue>(this IDictionary<TKey, TValue> dictionary, TKey key, TValue value) where TKey : notnull
+        public static bool TryAdd<TKey, TValue>(this IDictionary<TKey, TValue> dictionary, TKey key, TValue value)
         {
             if (dictionary == null)
             {
@@ -42,7 +42,7 @@ public static bool TryAdd<TKey, TValue>(this IDictionary<TKey, TValue> dictionar
             return false;
         }
 
-        public static bool Remove<TKey, TValue>(this IDictionary<TKey, TValue> dictionary, TKey key, [MaybeNullWhen(false)] out TValue value) where TKey : notnull
+        public static bool Remove<TKey, TValue>(this IDictionary<TKey, TValue> dictionary, TKey key, [MaybeNullWhen(false)] out TValue value)
         {
             if (dictionary == null)
             {
diff --git a/src/libraries/System.Private.CoreLib/src/System/Collections/Generic/IDictionary.cs b/src/libraries/System.Private.CoreLib/src/System/Collections/Generic/IDictionary.cs
index a79782c9d204c1..3e3fa3618cd0f1 100644
--- a/src/libraries/System.Private.CoreLib/src/System/Collections/Generic/IDictionary.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/Collections/Generic/IDictionary.cs
@@ -10,7 +10,7 @@ namespace System.Collections.Generic
     // Keys can be any non-null object.  Values can be any object.
     // You can look up a value in an IDictionary via the default indexed
     // property, Items.
-    public interface IDictionary<TKey, TValue> : ICollection<KeyValuePair<TKey, TValue>> where TKey : notnull
+    public interface IDictionary<TKey, TValue> : ICollection<KeyValuePair<TKey, TValue>>
     {
         // Interfaces are not serializable
         // The Item property provides methods to read and edit entries
diff --git a/src/libraries/System.Private.CoreLib/src/System/Collections/Generic/IReadOnlyDictionary.cs b/src/libraries/System.Private.CoreLib/src/System/Collections/Generic/IReadOnlyDictionary.cs
index af7ff0871dc1c9..47ec8eae759436 100644
--- a/src/libraries/System.Private.CoreLib/src/System/Collections/Generic/IReadOnlyDictionary.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/Collections/Generic/IReadOnlyDictionary.cs
@@ -7,7 +7,7 @@
 namespace System.Collections.Generic
 {
     // Provides a read-only view of a generic dictionary.
-    public interface IReadOnlyDictionary<TKey, TValue> : IReadOnlyCollection<KeyValuePair<TKey, TValue>> where TKey : notnull
+    public interface IReadOnlyDictionary<TKey, TValue> : IReadOnlyCollection<KeyValuePair<TKey, TValue>>
     {
         bool ContainsKey(TKey key);
         bool TryGetValue(TKey key, [MaybeNullWhen(false)] out TValue value);
diff --git a/src/libraries/System.Runtime/ref/System.Runtime.cs b/src/libraries/System.Runtime/ref/System.Runtime.cs
index c1ce2529f3303f..b39fd8be029ed3 100644
--- a/src/libraries/System.Runtime/ref/System.Runtime.cs
+++ b/src/libraries/System.Runtime/ref/System.Runtime.cs
@@ -3954,7 +3954,7 @@ public partial interface IComparer<in T>
     {
         int Compare([System.Diagnostics.CodeAnalysis.AllowNullAttribute] T x, [System.Diagnostics.CodeAnalysis.AllowNullAttribute] T y);
     }
-    public partial interface IDictionary<TKey, TValue> : System.Collections.Generic.ICollection<System.Collections.Generic.KeyValuePair<TKey, TValue>>, System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<TKey, TValue>>, System.Collections.IEnumerable where TKey : notnull
+    public partial interface IDictionary<TKey, TValue> : System.Collections.Generic.ICollection<System.Collections.Generic.KeyValuePair<TKey, TValue>>, System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<TKey, TValue>>, System.Collections.IEnumerable
     {
         TValue this[TKey key] { get; set; }
         System.Collections.Generic.ICollection<TKey> Keys { get; }
@@ -3988,7 +3988,7 @@ public partial interface IReadOnlyCollection<out T> : System.Collections.Generic
     {
         int Count { get; }
     }
-    public partial interface IReadOnlyDictionary<TKey, TValue> : System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<TKey, TValue>>, System.Collections.Generic.IReadOnlyCollection<System.Collections.Generic.KeyValuePair<TKey, TValue>>, System.Collections.IEnumerable where TKey : notnull
+    public partial interface IReadOnlyDictionary<TKey, TValue> : System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<TKey, TValue>>, System.Collections.Generic.IReadOnlyCollection<System.Collections.Generic.KeyValuePair<TKey, TValue>>, System.Collections.IEnumerable
     {
         TValue this[TKey key] { get; }
         System.Collections.Generic.IEnumerable<TKey> Keys { get; }