diff --git a/src/mzscheme/gc2/newgc.c b/src/mzscheme/gc2/newgc.c
index 71c477963a..5462977929 100644
--- a/src/mzscheme/gc2/newgc.c
+++ b/src/mzscheme/gc2/newgc.c
@@ -52,6 +52,12 @@
 #define PAGEMAP32_BITS(x) (NUM(x) >> LOG_APAGE_SIZE)
 #endif
 
+#if 0
+# define GC_ASSERT(x) assert(x)
+#else
+# define GC_ASSERT(x) /* empty */
+#endif
+
 /* the page type constants */
 enum {
   PAGE_TAGGED   = 0,
@@ -1827,7 +1833,7 @@ static void propagate_marks(NewGC *gc)
             if((unsigned long)mark_table[tag] < PAGE_TYPES) {
               /* atomic */
             } else {
-              assert(mark_table[tag]);
+              GC_ASSERT(mark_table[tag]);
               mark_table[tag](start); break;
             }
           }
@@ -1838,7 +1844,7 @@ static void propagate_marks(NewGC *gc)
                             unsigned short tag = *(unsigned short *)start;
                             end -= INSET_WORDS;
                             while(start < end) {
-                              assert(mark_table[tag]);
+                              GC_ASSERT(mark_table[tag]);
                               start += mark_table[tag](start);
                             }
                             break;
@@ -1853,7 +1859,7 @@ static void propagate_marks(NewGC *gc)
         case PAGE_TAGGED: 
           {
             unsigned short tag = *(unsigned short*)p;
-            assert(mark_table[tag]);
+            GC_ASSERT(mark_table[tag]);
             mark_table[tag](p);
             break;
           }
@@ -1869,7 +1875,7 @@ static void propagate_marks(NewGC *gc)
                             void **end = PPTR(info) + (info->size - INSET_WORDS);
                             unsigned short tag = *(unsigned short *)start;
                             while(start < end) {
-                              assert(mark_table[tag]);
+                              GC_ASSERT(mark_table[tag]);
                               start += mark_table[tag](start);
                             }
                             break;
diff --git a/src/mzscheme/gc2/sighand.c b/src/mzscheme/gc2/sighand.c
index 19e7a1130f..02b69091ad 100644
--- a/src/mzscheme/gc2/sighand.c
+++ b/src/mzscheme/gc2/sighand.c
@@ -18,6 +18,11 @@
 #include <sys/types.h>
 #include <unistd.h>
 
+#ifndef WAIT_FOR_GDB
+# define WAIT_FOR_GDB 0
+#endif
+
+#if WAIT_FOR_GDB
 static void launchgdb() {
   pid_t pid = getpid();
   char inbuffer[10];
@@ -31,13 +36,16 @@ static void launchgdb() {
     }
   }
 }
+#endif
 
 void fault_handler(int sn, struct siginfo *si, void *ctx)
 {
   void *p = si->si_addr;
   if (si->si_code != SEGV_ACCERR) { /*SEGV_MAPERR*/
     printf("SIGSEGV fault on %p\n", p);
+#if WAIT_FOR_GDB
     launchgdb();
+#endif
     abort();
   }
 
diff --git a/src/mzscheme/src/error.c b/src/mzscheme/src/error.c
index 446d809fe4..fcaa6a109e 100644
--- a/src/mzscheme/src/error.c
+++ b/src/mzscheme/src/error.c
@@ -2035,6 +2035,7 @@ static Scheme_Object *raise_syntax_error(int argc, Scheme_Object *argv[])
     while (SCHEME_PAIRP(extra_sources)) {
       if (!SCHEME_STXP(SCHEME_CAR(extra_sources)))
         break;
+      extra_sources = SCHEME_CDR(extra_sources);
     }
     if (!SCHEME_NULLP(extra_sources)) {
       scheme_wrong_type("raise-syntax-error", "list of syntax", 4, argc, argv);