diff --git a/SConstruct b/SConstruct
index 93b6cc9..ed03465 100644
--- a/SConstruct
+++ b/SConstruct
@@ -1,6 +1,13 @@
 # vim:filetype=python
 
+import os
+import sys
+
 env = Environment(LIBS = ['GL', 'GLU'])
 env.ParseConfig('sdl-config --cflags --libs')
 
 env.Program('wfobj-view', [Glob('*.cc'), Glob('wfobj/WFObj.cc')])
+
+if len(os.listdir('wfobj')) == 0:
+    sys.stderr.write('Warning: wfobj submodule not initialized\n')
+    sys.stderr.write('Warning: perhaps you should run `git submodule update --init`\n')