diff --git a/include/chibi/features.h b/include/chibi/features.h
index 2a0f52f7..3d18b43b 100644
--- a/include/chibi/features.h
+++ b/include/chibi/features.h
@@ -293,7 +293,7 @@
 #endif
 
 #ifndef SEXP_USE_WEAK_REFERENCES
-#define SEXP_USE_WEAK_REFERENCES 1
+#define SEXP_USE_WEAK_REFERENCES ! SEXP_USE_NO_FEATURES
 #endif
 
 #ifndef SEXP_USE_MALLOC
diff --git a/include/chibi/sexp.h b/include/chibi/sexp.h
index f96be078..60583cd5 100755
--- a/include/chibi/sexp.h
+++ b/include/chibi/sexp.h
@@ -865,7 +865,7 @@ SEXP_API sexp_heap sexp_global_heap;
 #endif
 
 #if SEXP_USE_GLOBAL_TYPES
-SEXP_API struct sexp_struct *sexp_type_specs;
+SEXP_API struct sexp_type_struct *sexp_type_specs;
 #define sexp_context_types(ctx)    sexp_type_specs
 #define sexp_type_by_index(ctx,i)  (&(sexp_context_types(ctx)[i]))
 #define sexp_context_num_types(ctx) sexp_num_types
diff --git a/sexp.c b/sexp.c
index 1e53a6ba..b4255f5d 100755
--- a/sexp.c
+++ b/sexp.c
@@ -161,9 +161,11 @@ sexp sexp_register_type_op (sexp ctx sexp_api_params(self, n), sexp name,
       len = type_array_size*2;
       if (len > SEXP_MAXIMUM_TYPES) len = SEXP_MAXIMUM_TYPES;
 #if SEXP_USE_GLOBAL_TYPES
-      new = malloc(len * sizeof(_sexp_type_specs[0]));
-      for (i=0; i<num_types; i++)
-        memcpy(&(new[i]), &(sexp_type_specs[i]), sizeof(_sexp_type_specs[0]));
+      new = malloc(len * sizeof(sexp_struct));
+      for (i=0; i<num_types; i++) {
+        new[i].tag = SEXP_TYPE;
+        memcpy(&(new[i].value), &(sexp_type_specs[i]), sizeof(_sexp_type_specs[0]));
+      }
       tmp = sexp_type_specs;
       sexp_type_specs = new;
       if (type_array_size > num_types) free(tmp);