diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index fa230df993..477bc1b54a 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,4 +1,4 @@
-*   SQLite3 adapter supports expression indexes
+*   SQLite3 adapter supports expression indexes.
 
     ```
     create_table :users do |t|
diff --git a/activerecord/lib/active_record/connection_adapters/sqlite3/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/sqlite3/schema_statements.rb
index 0e254455b6..46ca7e07a9 100644
--- a/activerecord/lib/active_record/connection_adapters/sqlite3/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/sqlite3/schema_statements.rb
@@ -21,23 +21,24 @@ module ActiveRecord
               WHERE name = #{quote(row['name'])} AND type = 'index'
             SQL
 
-            /\sON\s+"(\w+?)"\s+\((?<expressions>.+?)\)(\sWHERE\s+(?<where>.+))?$/i =~ index_sql
+            /\bON\b\s*"?(\w+?)"?\s*\((?<expressions>.+?)\)(?:\s*WHERE\b\s*(?<where>.+))?\z/i =~ index_sql
 
             columns = exec_query("PRAGMA index_info(#{quote(row['name'])})", "SCHEMA").map do |col|
               col["name"]
             end
 
-            if columns.any?(&:nil?) # index created with an expression
-              columns = expressions.split(", ").map { |e| e.gsub(/^\"|\"?$/, "") }
-            end
-
-            # Add info on sort order for columns (only desc order is explicitly specified, asc is
-            # the default)
             orders = {}
-            if index_sql # index_sql can be null in case of primary key indexes
-              index_sql.scan(/"(\w+)" DESC/).flatten.each { |order_column|
-                orders[order_column] = :desc
-              }
+
+            if columns.any?(&:nil?) # index created with an expression
+              columns = expressions
+            else
+              # Add info on sort order for columns (only desc order is explicitly specified,
+              # asc is the default)
+              if index_sql # index_sql can be null in case of primary key indexes
+                index_sql.scan(/"(\w+)" DESC/).flatten.each { |order_column|
+                  orders[order_column] = :desc
+                }
+              end
             end
 
             IndexDefinition.new(
diff --git a/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb b/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
index 51f4944808..d32fd5ea09 100644
--- a/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
@@ -487,9 +487,12 @@ module ActiveRecord
               name = name[1..-1]
             end
 
-            to_column_names = columns(to).map(&:name)
-            columns = index.columns.map { |c| rename[c] || c }.select do |column|
-              to_column_names.include?(column)
+            columns = index.columns
+            if columns.is_a?(Array)
+              to_column_names = columns(to).map(&:name)
+              columns = columns.map { |c| rename[c] || c }.select do |column|
+                to_column_names.include?(column)
+              end
             end
 
             unless columns.empty?
diff --git a/activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb b/activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb
index 320f6efd56..7b73621ed9 100644
--- a/activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb
+++ b/activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb
@@ -348,34 +348,35 @@ module ActiveRecord
       if ActiveRecord::Base.connection.supports_expression_index?
         def test_expression_index
           with_example_table do
-            @conn.add_index "ex", "abs(number)", name: "expression"
+            @conn.add_index "ex", "max(id, number)", name: "expression"
             index = @conn.indexes("ex").find { |idx| idx.name == "expression" }
-            assert_equal %w{ abs(number) }, index.columns
+            assert_equal "max(id, number)", index.columns
           end
         end
 
         def test_expression_index_with_where
           with_example_table do
-            @conn.add_index "ex", "id % 10, abs(number)", name: "expression", where: "id > 1000"
+            @conn.add_index "ex", "id % 10, max(id, number)", name: "expression", where: "id > 1000"
             index = @conn.indexes("ex").find { |idx| idx.name == "expression" }
-            assert_equal ["id % 10", "abs(number)"], index.columns
+            assert_equal "id % 10, max(id, number)", index.columns
             assert_equal "id > 1000", index.where
           end
         end
 
         def test_complicated_expression
           with_example_table do
-            @conn.add_index "ex", "id % 10, (CASE WHEN number > 0 THEN abs(number) END)", name: "expression"
+            @conn.execute "CREATE INDEX expression ON ex (id % 10, (CASE WHEN number > 0 THEN max(id, number) END))WHERE(id > 1000)"
             index = @conn.indexes("ex").find { |idx| idx.name == "expression" }
-            assert_equal ["id % 10", "(CASE WHEN number > 0 THEN abs(number) END)"], index.columns
+            assert_equal "id % 10, (CASE WHEN number > 0 THEN max(id, number) END)", index.columns
+            assert_equal "(id > 1000)", index.where
           end
         end
 
         def test_not_everything_an_expression
           with_example_table do
-            @conn.add_index "ex", %w{ id abs(number) }, name: "expression"
+            @conn.add_index "ex", "id, max(id, number)", name: "expression"
             index = @conn.indexes("ex").find { |idx| idx.name == "expression" }
-            assert_equal %w{ id abs(number) }.sort, index.columns.sort
+            assert_equal "id, max(id, number)", index.columns
           end
         end
       end