diff --git a/stim/parser/filename.h b/stim/parser/filename.h
index 62ba09f..167a717 100644
--- a/stim/parser/filename.h
+++ b/stim/parser/filename.h
@@ -213,7 +213,7 @@ public:
 		//this is OS dependent, so we're starting with Windows
 		//the Unix version requires Boost
 
-#elif _WIN32
+#ifdef _WIN32
 		stim::filename filepath(dir_fname());									//initialize filepath with the mask					
 
 		HANDLE            hFind = INVALID_HANDLE_VALUE;							//allocate data structures for looping through files
--
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