diff --git a/includes/newspack-listings-utils.php b/includes/newspack-listings-utils.php
index 8675c0a2..420bf297 100644
--- a/includes/newspack-listings-utils.php
+++ b/includes/newspack-listings-utils.php
@@ -107,7 +107,7 @@ function get_data_from_blocks( $blocks, $source ) {
 		}
 
 		// If the source has 'single' specified, only get data from the first found block instance.
-		if ( $source['single'] ) {
+		if ( isset( $source['single'] ) && ! empty( $source['single'] ) ) {
 			$matching_blocks = array_slice( $matching_blocks, 0, 1 );
 		}
 
@@ -138,7 +138,7 @@ function get_data_from_blocks( $blocks, $source ) {
 	}
 
 	// If the source has 'single' specified, only return data from the first found block instance.
-	if ( $source['single'] ) {
+	if ( isset( $source['single'] ) && ! empty( $source['single'] ) ) {
 		return array_shift( $data );
 	}