diff --git a/build/jam/RepositoryRules b/build/jam/RepositoryRules
index 52a7563fac..cb466acbc9 100644
--- a/build/jam/RepositoryRules
+++ b/build/jam/RepositoryRules
@@ -333,6 +333,11 @@ actions BootstrapRepositoryFetchPackage1
 
 	# make Haiku cross devel package path absolute
 	haikuCrossDevelPackage="$(2[1])"
+	if [ "x$haikuCrossDevelPackage" = "x" ]; then
+		echo "$portSpec does not have a cross-devel package defined!"
+		exit 1
+	fi
+
 	if [ "x$haikuCrossDevelPackage" = "x${haikuCrossDevelPackage#/}" ]; then
 		haikuCrossDevelPackage="`pwd`/$haikuCrossDevelPackage"
 	fi