diff --git a/build/jam/RepositoryRules b/build/jam/RepositoryRules
index 23e56dfd75..03a5430c2f 100644
--- a/build/jam/RepositoryRules
+++ b/build/jam/RepositoryRules
@@ -124,6 +124,11 @@ rule RemotePackageRepository repository : architecture : repositoryUrl
 {
 	repository = $(repository:G=repository) ;
 
+	if ! $(HOST_EXTENDED_REGEX_SED) {
+		ECHO "Variable HOST_EXTENDED_REGEX_SED not set. Please run ./configure or" ;
+		EXIT "specify it manually." ;
+	}
+
 	SetRepositoryMethod $(repository) : PackageFamily
 		: RemoteRepositoryPackageFamily ;
 	SetRepositoryMethod $(repository) : FetchPackage