diff --git a/install-php-extensions b/install-php-extensions
index 1d35852..8073322 100755
--- a/install-php-extensions
+++ b/install-php-extensions
@@ -927,6 +927,7 @@ buildRequiredPackageLists() {
 				buildRequiredPackageLists_volatile="$buildRequiredPackageLists_volatile zlib1g-dev"
 				;;
 			xmldiff@alpine)
+				buildRequiredPackageLists_persistent="$buildRequiredPackageLists_persistent libstdc++"
 				buildRequiredPackageLists_volatile="$buildRequiredPackageLists_volatile libxml2-dev"
 				;;
 			xmldiff@debian)