diff --git a/wp-includes/query.php b/wp-includes/query.php
index 2af594d47a..2f7f204274 100644
--- a/wp-includes/query.php
+++ b/wp-includes/query.php
@@ -1593,19 +1593,17 @@ class WP_Query {
 			);
 		}
 
-		if ( !$this->is_singular() ) {
-			foreach ( $tax_query as $query ) {
-				if ( 'IN' == $query['operator'] ) {
-					switch ( $query['taxonomy'] ) {
-						case 'category':
-							$this->is_category = true;
-							break;
-						case 'post_tag':
-							$this->is_tag = true;
-							break;
-						default:
-							$this->is_tax = true;
-					}
+		foreach ( $tax_query as $query ) {
+			if ( 'IN' == $query['operator'] ) {
+				switch ( $query['taxonomy'] ) {
+					case 'category':
+						$this->is_category = true;
+						break;
+					case 'post_tag':
+						$this->is_tag = true;
+						break;
+					default:
+						$this->is_tax = true;
 				}
 			}
 		}
@@ -1945,46 +1943,48 @@ class WP_Query {
 		$search = apply_filters_ref_array('posts_search', array( $search, &$this ) );
 
 		// Taxonomies
-		$this->tax_query = $this->parse_tax_query( $q );
-		if ( !empty( $this->tax_query ) ) {
-			$clauses = call_user_func_array( 'get_tax_sql', array( $this->tax_query, $wpdb->posts, 'ID', &$this) );
+		if ( !$this->is_singular ) {
+			$this->tax_query = $this->parse_tax_query( $q );
+			if ( !empty( $this->tax_query ) ) {
+				$clauses = call_user_func_array( 'get_tax_sql', array( $this->tax_query, $wpdb->posts, 'ID', &$this) );
 
-			$join .= $clauses['join'];
-			$where .= $clauses['where'];
+				$join .= $clauses['join'];
+				$where .= $clauses['where'];
 
-			if ( $this->is_tax ) {
-				if ( empty($post_type) ) {
-					$post_type = 'any';
-					$post_status_join = true;
-				} elseif ( in_array('attachment', (array) $post_type) ) {
-					$post_status_join = true;
-				}
-			}
-
-			// Back-compat
-			$tax_query_in = wp_list_filter( $this->tax_query, array( 'operator' => 'IN' ) );
-			if ( !empty( $tax_query_in ) ) {
-				if ( !isset( $q['taxonomy'] ) ) {
-					foreach ( $tax_query_in as $a_tax_query ) {
-						if ( !in_array( $a_tax_query['taxonomy'], array( 'category', 'post_tag' ) ) ) {
-							$q['taxonomy'] = $a_tax_query['taxonomy'];
-							if ( 'slug' == $a_tax_query['field'] )
-								$q['term'] = $a_tax_query['terms'][0];
-							else
-								$q['term_id'] = $a_tax_query['terms'][0];
-
-							break;
-						}
+				if ( $this->is_tax ) {
+					if ( empty($post_type) ) {
+						$post_type = 'any';
+						$post_status_join = true;
+					} elseif ( in_array('attachment', (array) $post_type) ) {
+						$post_status_join = true;
 					}
 				}
 
-				$cat_query = wp_list_filter( $tax_query_in, array( 'taxonomy' => 'category' ) );
-				if ( !empty( $cat_query ) ) {
-					$cat_query = reset( $cat_query );
-					$cat = get_term_by( $cat_query['field'], $cat_query['terms'][0], 'category' );
-					if ( $cat ) {
-						$this->set( 'cat', $cat->term_id );
-						$this->set( 'category_name', $cat->slug );
+				// Back-compat
+				$tax_query_in = wp_list_filter( $this->tax_query, array( 'operator' => 'IN' ) );
+				if ( !empty( $tax_query_in ) ) {
+					if ( !isset( $q['taxonomy'] ) ) {
+						foreach ( $tax_query_in as $a_tax_query ) {
+							if ( !in_array( $a_tax_query['taxonomy'], array( 'category', 'post_tag' ) ) ) {
+								$q['taxonomy'] = $a_tax_query['taxonomy'];
+								if ( 'slug' == $a_tax_query['field'] )
+									$q['term'] = $a_tax_query['terms'][0];
+								else
+									$q['term_id'] = $a_tax_query['terms'][0];
+
+								break;
+							}
+						}
+					}
+
+					$cat_query = wp_list_filter( $tax_query_in, array( 'taxonomy' => 'category' ) );
+					if ( !empty( $cat_query ) ) {
+						$cat_query = reset( $cat_query );
+						$cat = get_term_by( $cat_query['field'], $cat_query['terms'][0], 'category' );
+						if ( $cat ) {
+							$this->set( 'cat', $cat->term_id );
+							$this->set( 'category_name', $cat->slug );
+						}
 					}
 				}
 			}