diff --git a/src/wp-admin/includes/upgrade.php b/src/wp-admin/includes/upgrade.php
index 807673a7f0..6b04963aa8 100644
--- a/src/wp-admin/includes/upgrade.php
+++ b/src/wp-admin/includes/upgrade.php
@@ -2283,7 +2283,7 @@ function dbDelta( $queries = '', $execute = true ) {
 					$index_type = str_replace( 'INDEX', 'KEY', $index_type );
 
 					// Escape the index name with backticks. An index for a primary key has no name.
-					$index_name = ( 'PRIMARY KEY' === $index_type ) ? '' : '`' . $index_matches['index_name'] . '`';
+					$index_name = ( 'PRIMARY KEY' === $index_type ) ? '' : '`' . strtolower( $index_matches['index_name'] ) . '`';
 
 					// Parse the columns. Multiple columns are separated by a comma.
 					$index_columns = array_map( 'trim', explode( ',', $index_matches['index_columns'] ) );
@@ -2407,7 +2407,7 @@ function dbDelta( $queries = '', $execute = true ) {
 			foreach ($tableindices as $tableindex) {
 
 				// Add the index to the index data array.
-				$keyname = $tableindex->Key_name;
+				$keyname = strtolower( $tableindex->Key_name );
 				$index_ary[$keyname]['columns'][] = array('fieldname' => $tableindex->Column_name, 'subpart' => $tableindex->Sub_part);
 				$index_ary[$keyname]['unique'] = ($tableindex->Non_unique == 0)?true:false;
 				$index_ary[$keyname]['index_type'] = $tableindex->Index_type;
@@ -2418,7 +2418,7 @@ function dbDelta( $queries = '', $execute = true ) {
 
 				// Build a create string to compare to the query.
 				$index_string = '';
-				if ($index_name == 'PRIMARY') {
+				if ($index_name == 'primary') {
 					$index_string .= 'PRIMARY ';
 				} elseif ( $index_data['unique'] ) {
 					$index_string .= 'UNIQUE ';
@@ -2430,7 +2430,7 @@ function dbDelta( $queries = '', $execute = true ) {
 					$index_string .= 'SPATIAL ';
 				}
 				$index_string .= 'KEY ';
-				if ( 'PRIMARY' !== $index_name  ) {
+				if ( 'primary' !== $index_name  ) {
 					$index_string .= '`' . $index_name . '`';
 				}
 				$index_columns = '';
diff --git a/tests/phpunit/tests/dbdelta.php b/tests/phpunit/tests/dbdelta.php
index c4b23b0274..ce4f78c793 100644
--- a/tests/phpunit/tests/dbdelta.php
+++ b/tests/phpunit/tests/dbdelta.php
@@ -802,6 +802,29 @@ class Tests_dbDelta extends WP_UnitTestCase {
 		$this->assertEmpty( $updates );
 	}
 
+	/**
+	 * @ticket 34874
+	 */
+	function test_key_names_are_not_case_sensitive_and_do_not_recreate_indices() {
+		global $wpdb;
+
+		$updates = dbDelta(
+			"
+			CREATE TABLE {$wpdb->prefix}dbdelta_test (
+				id bigint(20) NOT NULL AUTO_INCREMENT,
+				column_1 varchar(255) NOT NULL,
+				column_2 text,
+				column_3 blob,
+				PRIMARY KEY  (id),
+				KEY KEY_1 (column_1),
+				KEY compOUND_key (id,column_1),
+				FULLTEXT KEY FULLtext_kEY (column_1)
+			) ENGINE=MyISAM
+			", false );
+
+		$this->assertEmpty( $updates );
+	}
+
 	/**
 	 * @ticket 31679
 	 */