diff --git a/src/if_mzsch.c b/src/if_mzsch.c
index 6a34ad3..4874851 100644
--- a/src/if_mzsch.c
+++ b/src/if_mzsch.c
@@ -24,6 +24,10 @@
 #include "vim.h"
 #include "if_mzsch.h"
 
+/* Only do the following when the feature is enabled.  Needed for "make
+ * depend". */
+#if defined(FEAT_MZSCHEME) || defined(PROTO)
+
 /* Base data structures */
 #define SCHEME_VIMBUFFERP(obj)  SAME_TYPE(SCHEME_TYPE(obj), mz_buffer_type)
 #define SCHEME_VIMWINDOWP(obj)  SAME_TYPE(SCHEME_TYPE(obj), mz_window_type)
@@ -2709,3 +2713,5 @@
     return scheme_void;
 }
 #endif
+
+#endif