diff --git a/package/pkg-generic.mk b/package/pkg-generic.mk
index 5201fcac87..de2fb0705b 100644
--- a/package/pkg-generic.mk
+++ b/package/pkg-generic.mk
@@ -847,6 +847,10 @@ endif
 	$(1)-source \
 	$(1)-source-check
 
+ifeq ($$(patsubst %/,ERROR,$$($(2)_SITE)),ERROR)
+$$(error $(2)_SITE ($$($(2)_SITE)) cannot have a trailing slash)
+endif
+
 endif # $(2)_KCONFIG_VAR
 endef # inner-generic-package