diff --git a/src/OpenIddict.EntityFramework/Models/OpenIddictAuthorization.cs b/src/OpenIddict.EntityFramework/Models/OpenIddictAuthorization.cs
index 03f2b4b5..bf111603 100644
--- a/src/OpenIddict.EntityFramework/Models/OpenIddictAuthorization.cs
+++ b/src/OpenIddict.EntityFramework/Models/OpenIddictAuthorization.cs
@@ -45,11 +45,5 @@ namespace OpenIddict {
         /// associated with the current authorization.
         /// </summary>
         public virtual IList<TToken> Tokens { get; } = new List<TToken>();
-
-        /// <summary>
-        /// Gets or sets the identifier of the user profile
-        /// associated with the current authorization.
-        /// </summary>
-        public virtual TKey UserId { get; set; }
     }
 }
diff --git a/src/OpenIddict.EntityFramework/Models/OpenIddictToken.cs b/src/OpenIddict.EntityFramework/Models/OpenIddictToken.cs
index 487830ec..6b14f73e 100644
--- a/src/OpenIddict.EntityFramework/Models/OpenIddictToken.cs
+++ b/src/OpenIddict.EntityFramework/Models/OpenIddictToken.cs
@@ -21,13 +21,6 @@ namespace OpenIddict {
     /// Represents an OpenIddict token.
     /// </summary>
     public class OpenIddictToken<TKey> where TKey : IEquatable<TKey> {
-        /// <summary>
-        /// Gets or sets the identifier of the authorization attached with the current token.
-        /// This property may be null if the token was issued without
-        /// requiring the user consent or is bound to a client application.
-        /// </summary>
-        public virtual TKey AuthorizationId { get; set; }
-
         /// <summary>
         /// Gets or sets the unique identifier
         /// associated with the current token.
@@ -38,11 +31,5 @@ namespace OpenIddict {
         /// Gets or sets the type of the current token.
         /// </summary>
         public virtual string Type { get; set; }
-
-        /// <summary>
-        /// Gets or sets the identifier of the user attached with the current token.
-        /// This property is null if the token represents a client application.
-        /// </summary>
-        public virtual TKey UserId { get; set; }
     }
 }
diff --git a/src/OpenIddict.EntityFramework/OpenIddictContext.cs b/src/OpenIddict.EntityFramework/OpenIddictContext.cs
index 87b28970..a6957abb 100644
--- a/src/OpenIddict.EntityFramework/OpenIddictContext.cs
+++ b/src/OpenIddict.EntityFramework/OpenIddictContext.cs
@@ -127,6 +127,10 @@ namespace OpenIddict {
         protected override void OnModelCreating(ModelBuilder builder) {
             base.OnModelCreating(builder);
 
+            // Warning: optional foreign keys MUST NOT be added as CLR properties because
+            // Entity Framework would throw an exception due to the TKey generic parameter
+            // being non-nullable when using value types like short, int, long or Guid.
+
             // Configure the TApplication entity.
             builder.Entity<TApplication>(entity => {
                 entity.HasKey(application => application.Id);
@@ -140,7 +144,7 @@ namespace OpenIddict {
 
                 entity.HasMany(authorization => authorization.Tokens)
                       .WithOne()
-                      .HasForeignKey(token => token.AuthorizationId)
+                      .HasForeignKey("AuthorizationId")
                       .IsRequired(required: false);
 
                 entity.ToTable("OpenIddictAuthorizations");
@@ -164,12 +168,12 @@ namespace OpenIddict {
             builder.Entity<TUser>(entity => {
                 entity.HasMany(user => user.Authorizations)
                       .WithOne()
-                      .HasForeignKey(authorization => authorization.UserId)
+                      .HasForeignKey("UserId")
                       .IsRequired(required: false);
 
                 entity.HasMany(user => user.Tokens)
                       .WithOne()
-                      .HasForeignKey(token => token.UserId)
+                      .HasForeignKey("UserId")
                       .IsRequired(required: false);
             });
         }