diff --git a/lib/active_record/connection_adapters/sqlserver/schema_statements.rb b/lib/active_record/connection_adapters/sqlserver/schema_statements.rb
index 521f51ee2..01e4e45b8 100644
--- a/lib/active_record/connection_adapters/sqlserver/schema_statements.rb
+++ b/lib/active_record/connection_adapters/sqlserver/schema_statements.rb
@@ -472,6 +472,7 @@ def column_definitions_sql(database, identifier)
               AND c.default_object_id = d.object_id
             LEFT OUTER JOIN #{database}.sys.key_constraints k
               ON c.object_id = k.parent_object_id
+              AND k.type = 'PK'
             LEFT OUTER JOIN #{database}.sys.index_columns ic
               ON k.parent_object_id = ic.object_id
               AND k.unique_index_id = ic.index_id
diff --git a/test/cases/schema_dumper_test_sqlserver.rb b/test/cases/schema_dumper_test_sqlserver.rb
index 3a9a3ad8c..4e30dd458 100644
--- a/test/cases/schema_dumper_test_sqlserver.rb
+++ b/test/cases/schema_dumper_test_sqlserver.rb
@@ -135,6 +135,12 @@ class SchemaDumperTestSQLServer < ActiveRecord::TestCase
     assert_line :name, type: "string", limit: nil, default: nil, collation: nil
   end
 
+  it "dumps field with unique key constraints only once" do
+    output = generate_schema_for_table "unique_key_dumped_table"
+
+    _(output.scan('t.integer "unique_field"').length).must_equal(1)
+  end
+
   private
 
   def generate_schema_for_table(*table_names)
diff --git a/test/schema/sqlserver_specific_schema.rb b/test/schema/sqlserver_specific_schema.rb
index bae4e4b78..9964cef4f 100644
--- a/test/schema/sqlserver_specific_schema.rb
+++ b/test/schema/sqlserver_specific_schema.rb
@@ -277,4 +277,14 @@
       field_2 int NOT NULL PRIMARY KEY,
     )
   SCHEMATESTMULTIPLESCHEMA
+
+  execute "IF EXISTS(SELECT * FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME = 'unique_key_dumped_table') DROP TABLE unique_key_dumped_table"
+  execute <<-SQLSERVERUNIQUEKEYS
+    CREATE TABLE unique_key_dumped_table (
+      id int IDENTITY(1,1) NOT NULL,
+      unique_field int DEFAULT 0 NOT NULL,
+      CONSTRAINT IX_UNIQUE_KEY UNIQUE (unique_field),
+      CONSTRAINT PK_UNIQUE_KEY PRIMARY KEY (id)
+    );
+  SQLSERVERUNIQUEKEYS
 end