diff --git a/frontends/verilog/preproc.h b/frontends/verilog/preproc.h
index 51562787a..fd2e99f3d 100644
--- a/frontends/verilog/preproc.h
+++ b/frontends/verilog/preproc.h
@@ -73,12 +73,12 @@ struct define_map_t;
 
 std::string
 frontend_verilog_preproc(std::istream                 &f,
-                         std::string                   filename,
-                         const define_map_t           &pre_defines,
-                         define_map_t                 &global_defines_cache,
-                         const std::list<std::string> &include_dirs,
-						 VERILOG_FRONTEND::ParseState &parse_state,
-						 VERILOG_FRONTEND::ParseMode  &parse_mode);
+						std::string                   filename,
+						const define_map_t           &pre_defines,
+						define_map_t                 &global_defines_cache,
+						const std::list<std::string> &include_dirs,
+						VERILOG_FRONTEND::ParseState &parse_state,
+						VERILOG_FRONTEND::ParseMode  &parse_mode);
 
 YOSYS_NAMESPACE_END