diff --git a/src/EFCore/Metadata/Internal/InternalEntityTypeBuilder.cs b/src/EFCore/Metadata/Internal/InternalEntityTypeBuilder.cs
index 191c53ebe52..5828f930dc5 100644
--- a/src/EFCore/Metadata/Internal/InternalEntityTypeBuilder.cs
+++ b/src/EFCore/Metadata/Internal/InternalEntityTypeBuilder.cs
@@ -930,11 +930,11 @@ public void Attach(InternalEntityTypeBuilder entityTypeBuilder)
             }
         }
 
-        private List<ForeignKey> FindConflictingRelationships(
+        private IEnumerable<ForeignKey> FindConflictingRelationships(
             EntityType baseEntityType,
             ConfigurationSource configurationSource)
         {
-            var relationshipsToBeDetached = new List<ForeignKey>();
+            var relationshipsToBeDetached = new HashSet<ForeignKey>();
             foreach (var navigation in Metadata.GetDerivedNavigationsInclusive())
             {
                 if (!navigation.ForeignKey.GetConfigurationSource().Overrides(
@@ -1739,16 +1739,16 @@ private InternalRelationshipBuilder Owns(
                 var existingNavigation = Metadata
                     .FindNavigationsInHierarchy(navigation.Name)
                     .SingleOrDefault(n => n.GetTargetType().Name == targetEntityType.Name && n.GetTargetType().HasDefiningNavigation());
-                
+
                 var builder = existingNavigation?.ForeignKey.Builder;
-                
+
                 if (builder != null)
                 {
                     builder = builder.RelatedEntityTypes(Metadata, existingNavigation.GetTargetType(), configurationSource);
                     builder = builder?.IsRequired(true, configurationSource);
                     builder = builder?.IsOwnership(true, configurationSource);
                     builder = builder?.Navigations(inverse, navigation, configurationSource);
-                    
+
                     return builder == null ? null : batch.Run(builder);
                 }
 
diff --git a/test/EFCore.Tests/ModelBuilding/InheritanceTestBase.cs b/test/EFCore.Tests/ModelBuilding/InheritanceTestBase.cs
index 85217d8c061..22d8e1e6d04 100644
--- a/test/EFCore.Tests/ModelBuilding/InheritanceTestBase.cs
+++ b/test/EFCore.Tests/ModelBuilding/InheritanceTestBase.cs
@@ -8,6 +8,7 @@
 using Microsoft.EntityFrameworkCore.TestUtilities;
 using Xunit;
 
+// ReSharper disable InconsistentNaming
 namespace Microsoft.EntityFrameworkCore.ModelBuilding
 {
     public abstract partial class ModelBuilderTest
@@ -68,6 +69,22 @@ public virtual void Base_types_are_mapped_correctly_if_discovered_last()
                 Assert.Same(derived, moreDerived.BaseType);
             }
 
+            [Fact]
+            public virtual void Can_map_derived_self_ref_many_to_one()
+            {
+                var modelBuilder = CreateModelBuilder();
+
+                modelBuilder.Entity<SelfRefManyToOneDerived>();
+                modelBuilder.Entity<SelfRefManyToOne>();
+
+                modelBuilder.Validate();
+
+                var model = modelBuilder.Model;
+                Assert.Equal(0, model.FindEntityType(typeof(SelfRefManyToOneDerived)).GetDeclaredProperties().Count());
+                Assert.NotNull(model.FindEntityType(typeof(SelfRefManyToOne)).FindNavigation(nameof(SelfRefManyToOne.SelfRef1)));
+                Assert.NotNull(model.FindEntityType(typeof(SelfRefManyToOne)).FindNavigation(nameof(SelfRefManyToOne.SelfRef2)));
+            }
+
             [Fact]
             public virtual void Can_set_and_remove_base_type()
             {
diff --git a/test/EFCore.Tests/ModelBuilding/TestModel.cs b/test/EFCore.Tests/ModelBuilding/TestModel.cs
index 6160b33e666..fb7fd344e21 100644
--- a/test/EFCore.Tests/ModelBuilding/TestModel.cs
+++ b/test/EFCore.Tests/ModelBuilding/TestModel.cs
@@ -222,6 +222,18 @@ protected class SelfRef
             public int SelfRefId { get; set; }
         }
 
+        protected class SelfRefManyToOne
+        {
+            public int Id { get; set; }
+            public SelfRefManyToOne SelfRef1 { get; set; }
+            public ICollection<SelfRefManyToOne> SelfRef2 { get; set; }
+            public int SelfRefId { get; set; }
+        }
+
+        protected class SelfRefManyToOneDerived : SelfRefManyToOne
+        {
+        }
+
         protected class Book
         {
             public static readonly PropertyInfo BookDetailsNavigation = typeof(Book).GetProperty("Details");