diff --git a/apicheck.mk b/apicheck.mk
index 3437a82..b7aa05c 100644
--- a/apicheck.mk
+++ b/apicheck.mk
@@ -68,7 +68,7 @@
 
 # Check that the API we're building hasn't broken the last-released SDK version
 # if it exists
-ifdef $(last_released_sdk_$(support_module))
+ifneq ($(last_released_sdk_$(support_module)),)
 $(eval $(call check-api, \
     $(support_module)-checkapi-last, \
     $(support_module_api_dir)/$(last_released_sdk_$(support_module)).txt, \