diff --git a/src/igc.c b/src/igc.c
index dfb25d6c824..5de83980863 100644
--- a/src/igc.c
+++ b/src/igc.c
@@ -73,7 +73,7 @@
 static void
 igc_assert_fail (const char *file, unsigned line, const char *msg)
 {
-  extern void die (const char *, const char *, int);
+  //extern void die (const char *, const char *, int);
   die (msg, file, line);
 }
 
@@ -81,7 +81,7 @@ igc_assert_fail (const char *file, unsigned line, const char *msg)
 # define igc_assert(expr)                         \
    if (!(expr))                                   \
      igc_assert_fail (__FILE__, __LINE__, #expr); \
-   else
+   /* else */
 #else
 # define igc_assert(expr) (void) 9
 #endif
@@ -122,7 +122,7 @@ is_aligned (const mps_addr_t addr)
 #define IGC_CHECK_RES(res) \
   if ((res) != MPS_RES_OK) \
     emacs_abort ();        \
-  else
+  /* else */
 
 #define IGC_WITH_PARKED(gc)                        \
   for (int i = (mps_arena_park (gc->arena), 1); i; \
@@ -801,6 +801,7 @@ scan_pure (mps_ss_t ss, void *start, void *end, void *closure)
   MPS_SCAN_BEGIN (ss)
   {
     igc_assert (start == (void *) pure);
+    extern ptrdiff_t pure_bytes_used_lisp;
     end = (char *) pure + pure_bytes_used_lisp;
     if (end > start)
       IGC_FIX_CALL (ss, scan_ambig (ss, start, end, NULL));
@@ -954,6 +955,7 @@ fix_itree_node (mps_ss_t ss, struct itree_node *n)
 static mps_res_t
 fix_image (mps_ss_t ss, struct image *i)
 {
+#ifdef HAVE_WINDOW_SYSTEM
   MPS_SCAN_BEGIN (ss)
   {
     IGC_FIX12_OBJ (ss, &i->spec);
@@ -964,6 +966,7 @@ fix_image (mps_ss_t ss, struct image *i)
   }
   MPS_SCAN_END (ss);
   return MPS_RES_OK;
+#endif
 }
 
 static mps_res_t
@@ -2342,6 +2345,7 @@ thread_ap (enum igc_obj_type type)
     case IGC_OBJ_FLOAT:
       return t->d.leaf_ap;
     }
+  emacs_abort ();
 }
 
 /* Conditional breakpoints can be so slow that it is often more
@@ -2572,12 +2576,14 @@ igc_make_itree_node (void)
   return n;
 }
 
+#ifdef HAVE_WINDOW_SYSTEM
 struct image *
 igc_make_image (void)
 {
   struct image *img = alloc (sizeof *img, IGC_OBJ_IMAGE, PVEC_FREE);
   return img;
 }
+#endif
 
 struct face *
 igc_make_face (void)