diff --git a/map_data_rules.mk b/map_data_rules.mk
index 5a7d9dd84..0203b383d 100755
--- a/map_data_rules.mk
+++ b/map_data_rules.mk
@@ -3,7 +3,7 @@
 MAPS_DIR = $(DATA_ASM_SUBDIR)/maps
 LAYOUTS_DIR = $(DATA_ASM_SUBDIR)/layouts
 
-MAP_DIRS := $(dir $(wildcard $(MAPS_DIR)/*/))
+MAP_DIRS := $(dir $(wildcard $(MAPS_DIR)/*/map.json))
 MAP_CONNECTIONS := $(patsubst $(MAPS_DIR)/%/,$(MAPS_DIR)/%/connections.inc,$(MAP_DIRS))
 MAP_EVENTS := $(patsubst $(MAPS_DIR)/%/,$(MAPS_DIR)/%/events.inc,$(MAP_DIRS))
 MAP_HEADERS := $(patsubst $(MAPS_DIR)/%/,$(MAPS_DIR)/%/header.inc,$(MAP_DIRS))