diff --git a/djvu.c b/djvu.c
index 3da999f88..d3186cc9a 100644
--- a/djvu.c
+++ b/djvu.c
@@ -117,6 +117,7 @@ static int closeDocument(lua_State *L) {
 
 		doc->context = NULL;
 	}
+	return 0;
 }
 
 static int getNumberOfPages(lua_State *L) {
diff --git a/pdf.c b/pdf.c
index 2551be985..e079c54b6 100644
--- a/pdf.c
+++ b/pdf.c
@@ -79,6 +79,7 @@ static int closeDocument(lua_State *L) {
 		fz_free_context(doc->context);
 		doc->context = NULL;
 	}
+	return 0;
 }
 
 static int getNumberOfPages(lua_State *L) {