diff --git a/src/wp-includes/meta.php b/src/wp-includes/meta.php
index dc19833612..b3a06c9681 100644
--- a/src/wp-includes/meta.php
+++ b/src/wp-includes/meta.php
@@ -753,7 +753,7 @@ class WP_Meta_Query {
 		// Split out the meta_key only queries (we can only do this for OR)
 		if ( 'OR' == $this->relation ) {
 			foreach ( $this->queries as $k => $q ) {
-				if ( ! array_key_exists( 'value', $q ) && ! empty( $q['key'] ) )
+				if ( ( empty( $q['compare'] ) || 'NOT EXISTS' != $q['compare'] ) && ! array_key_exists( 'value', $q ) && ! empty( $q['key'] ) )
 					$key_only_queries[$k] = $q;
 				else
 					$queries[$k] = $q;
diff --git a/tests/phpunit/tests/meta/query.php b/tests/phpunit/tests/meta/query.php
index ef668ab04a..fdd7693f79 100644
--- a/tests/phpunit/tests/meta/query.php
+++ b/tests/phpunit/tests/meta/query.php
@@ -152,4 +152,46 @@ class Tests_Meta_Query extends WP_UnitTestCase {
 
 		$this->assertEquals( 'CHAR', $query->get_cast_for_type( 'ANYTHING ELSE' ) );
 	}
+
+	function test_not_exists() {
+		global $wpdb;
+
+		$query = new WP_Meta_Query( array(
+			'relation' => 'OR',
+			array(
+				'key' => 'exclude',
+				'compare' => 'NOT EXISTS'
+			),
+			array(
+				'key' => 'exclude',
+				'compare' => '!=',
+				'value' => '1'
+			),
+		) );
+
+		$sql = $query->get_sql( 'post', $wpdb->posts, 'ID', $this );
+		$this->assertNotContains( "{$wpdb->postmeta}.meta_key = 'exclude'\nOR", $sql['where'] );
+		$this->assertContains( "{$wpdb->postmeta}.post_id IS NULL", $sql['where'] );
+	}
+
+	function test_empty_compare() {
+		global $wpdb;
+
+		$query = new WP_Meta_Query( array(
+			'relation' => 'OR',
+			array(
+				'key' => 'exclude',
+				'compare' => ''
+			),
+			array(
+				'key' => 'exclude',
+				'compare' => '!=',
+				'value' => '1'
+			),
+		) );
+
+		$sql = $query->get_sql( 'post', $wpdb->posts, 'ID', $this );
+		$this->assertContains( "{$wpdb->postmeta}.meta_key = 'exclude'\nOR", $sql['where'] );
+		$this->assertNotContains( "{$wpdb->postmeta}.post_id IS NULL", $sql['where'] );
+	}
 }