diff --git a/src/if_mzsch.c b/src/if_mzsch.c
index 9038195..4f08577 100644
--- a/src/if_mzsch.c
+++ b/src/if_mzsch.c
@@ -29,6 +29,19 @@
  * depend". */
 #if defined(FEAT_MZSCHEME) || defined(PROTO)
 
+#ifdef PROTO
+typedef int Scheme_Object;
+typedef int Scheme_Closed_Prim;
+typedef int Scheme_Env;
+typedef int Scheme_Hash_Table;
+typedef int Scheme_Type;
+typedef int Scheme_Thread;
+typedef int Scheme_Closed_Prim;
+typedef int mzshort;
+typedef int Scheme_Prim;
+typedef int HINSTANCE;
+#endif
+
 /*
  * scheme_register_tls_space is only available on 32-bit Windows until
  * racket-6.3.  See
@@ -248,7 +261,7 @@
 # define BUFFER_REF(buf) (vim_mz_buffer *)((buf)->b_mzscheme_ref)
 #endif
 
-#ifdef DYNAMIC_MZSCHEME
+#if defined(DYNAMIC_MZSCHEME) || defined(PROTO)
 static Scheme_Object *dll_scheme_eof;
 static Scheme_Object *dll_scheme_false;
 static Scheme_Object *dll_scheme_void;
@@ -406,6 +419,8 @@
 static void (*dll_scheme_set_config_path)(Scheme_Object *p);
 # endif
 
+#if defined(DYNAMIC_MZSCHEME) /* not when defined(PROTO) */
+
 /* arrays are imported directly */
 # define scheme_eof dll_scheme_eof
 # define scheme_false dll_scheme_false
@@ -539,6 +554,8 @@
 #  endif
 # endif
 
+#endif
+
 typedef struct
 {
     char    *name;
@@ -866,7 +883,7 @@
 }
 #endif
 
-#ifdef MZSCHEME_GUI_THREADS
+#if defined(MZSCHEME_GUI_THREADS) || defined(PROTO)
 static void setup_timer(void);
 static void remove_timer(void);