diff --git a/fsfw.mk b/fsfw.mk
index c025ba23d..c2c6e7475 100644
--- a/fsfw.mk
+++ b/fsfw.mk
@@ -35,7 +35,7 @@ CXXSRC += $(wildcard $(FRAMEWORK_PATH)/osal/FreeRTOS/*.cpp)
 else ifeq ($(OS_FSFW),host)
 CXXSRC += $(wildcard $(FRAMEWORK_PATH)/osal/host/*.cpp)
 else
-$(error invalid OS specified, valid OS are rtems, linux, freeRTOS, host)
+$(error invalid OS_FSFW specified, valid OS_FSFW are rtems, linux, freeRTOS, host)
 endif
 
 CXXSRC += $(wildcard $(FRAMEWORK_PATH)/parameters/*.cpp)