diff --git a/LOG b/LOG
index 018fc06a5..1b35a37cb 100644
--- a/LOG
+++ b/LOG
@@ -2398,3 +2398,6 @@
 - reduce allocation and copying for certain cases in bytevector->string
     mats/io.ms release_notes/release_notes.stex s/io.ss
 - update zlib to version 1.3
+- repair collector handling of weak pointers when the max target generation
+  is greater than the minimum target generation
+    c/gc.c mats/4.ms
diff --git a/c/gc.c b/c/gc.c
index 425d92f57..ea6765601 100644
--- a/c/gc.c
+++ b/c/gc.c
@@ -64,7 +64,7 @@ static void sweep_locked_ptrs(ptr *p, iptr n FORMAL_CTGS);
 static void sweep_locked(ptr tc, ptr p, IBOOL sweep_pure FORMAL_CTGS);
 static ptr copy_stack(ptr old, iptr *length, iptr clength FORMAL_CTGS);
 static void resweep_weak_pairs(ONLY_FORMAL_CTGS);
-static void forward_or_bwp(ptr *pp, ptr p);
+static void forward_or_bwp(IGEN from_g, ptr *pp, ptr p FORMAL_CTGS);
 static void sweep_generation(ptr tc FORMAL_CTGS);
 #ifndef NO_LOCKED_OLDSPACE_OBJECTS
 static iptr size_object(ptr p);
@@ -1110,12 +1110,12 @@ void GCENTRY GCENTRY_PROTO(ptr tc, IGEN max_cg, IGEN min_tg, IGEN max_tg) {
       for (ls = S_G.locked_objects[g]; ls != Snil; ls = Scdr(ls)) {
         ptr x = Scar(ls);
         if (Spairp(x) && (SPACE(x) & ~(space_old|space_locked)) == space_weakpair)
-          forward_or_bwp(&INITCAR(x), Scar(x));
+          forward_or_bwp(g, &INITCAR(x), Scar(x) ACTUAL_CTGS);
       }
       for (ls = S_G.unlocked_objects[g]; ls != Snil; ls = Scdr(ls)) {
         ptr x = Scar(ls);
         if (Spairp(x) && (SPACE(x) & ~(space_old|space_locked)) == space_weakpair)
-          forward_or_bwp(&INITCAR(x), Scar(x));
+          forward_or_bwp(g, &INITCAR(x), Scar(x) ACTUAL_CTGS);
       }
     }
 
@@ -1128,7 +1128,7 @@ void GCENTRY GCENTRY_PROTO(ptr tc, IGEN max_cg, IGEN min_tg, IGEN max_tg) {
       x = *(vp = &INITVECTIT(v, 0));
       do {
         if (Spairp(x) && (SPACE(x) & ~(space_old|space_locked)) == space_weakpair) {
-          forward_or_bwp(&INITCAR(x), Scar(x));
+          forward_or_bwp(GENERATION(x), &INITCAR(x), Scar(x) ACTUAL_CTGS);
         }
       } while (--i != 0 && (x = *++vp) != MAXPTR);
     }
@@ -1392,13 +1392,14 @@ static void resweep_weak_pairs(ONLY_FORMAL_CTGS) {
     for (from_g = MIN_TG; from_g <= MAX_TG; from_g += 1) {
       sweep_loc[from_g][space_weakpair] = orig_next_loc[from_g][space_weakpair];
       sweep_space(space_weakpair, from_g, {
-          forward_or_bwp(pp, p);
+          forward_or_bwp(from_g, pp, p ACTUAL_CTGS);
           pp += 2;
       })
     }
 }
 
-static void forward_or_bwp(ptr *pp, ptr p) {
+#ifdef NO_DIRTY_NEWSPACE_POINTERS
+static void forward_or_bwp(UNUSED IGEN from_g, ptr *pp, ptr p) {
   seginfo *si;
  /* adapted from relocate */
   if (!IMMEDIATE(p) && (si = MaybeSegInfo(ptr_get_segment(p))) != NULL && si->space & space_old && !locked(p)) {
@@ -1409,6 +1410,27 @@ static void forward_or_bwp(ptr *pp, ptr p) {
     }
   }
 }
+#else
+static void forward_or_bwp(IGEN from_g, ptr *pp, ptr p FORMAL_CTGS) {
+  seginfo *si;
+ /* adapted from relocate_impure */
+  if (!IMMEDIATE(p) && (si = MaybeSegInfo(ptr_get_segment(p))) != NULL) {
+    IGEN __to_g;
+    if (si->space & space_old && !locked(p)) {
+      if (FWDMARKER(p) == forward_marker && TYPEBITS(p) != type_flonum) {
+        *pp = FWDADDRESS(p);
+        __to_g = compute_target_generation(si->generation ACTUAL_CTGS);
+      } else {
+        *pp = Sbwp_object;
+        __to_g = static_generation;
+      }
+    } else {
+      __to_g = compute_target_generation(si->generation ACTUAL_CTGS);
+    }
+    if (__to_g < from_g) record_new_dirty_card(pp, __to_g);
+  }
+}
+#endif
 
 static void sweep_generation(ptr tc FORMAL_CTGS) {
   IGEN from_g; ptr *slp, *nlp; ptr *pp, p, *nl;
diff --git a/mats/4.ms b/mats/4.ms
index d66ca7c63..8fb991984 100644
--- a/mats/4.ms
+++ b/mats/4.ms
@@ -3758,6 +3758,22 @@
               (begin (set-car! x (cons 'd 'e)) (equal? (car x) '(d . e)))
               (begin (collect (collect-maximum-generation))
                      (bwp-object? (car x))))))
+   ;; check interaction of weak pairs, generations, and specific target generations for collection
+   (with-interrupts-disabled
+    (parameterize ([#%$enable-check-heap #t])
+      (let ([key "key"])
+        (let ([e (weak-cons key #f)])
+          (collect 0 1 1)
+          (let ([key2 (gensym key)])
+            ;; e is gen 1, key2 is gen 0:
+            (set-car! e key2)
+            (collect 1 1 2)
+            ;; Now, e is gen 1, key2 is gen 0
+            (and (eq? (car e) key2)
+                 (begin
+                   (collect 1 2 2)
+                   ;; Check that the GC update the reference to `key2` in `e`:
+                   (eq? (car e) key2))))))))
  )
 
 (mat ephemeron
@@ -3932,20 +3948,21 @@
    ;; ----------------------------------------
    ;; Check interaction of mutation and incremental generation promotion
 
-   (parameterize ([collect-request-handler void] [collect-maximum-generation (max (collect-maximum-generation) 2)])
-    (let ([key "key"])
-      (let ([e (ephemeron-cons key #f)])
-        (collect 0 1 1)
-        (let ([key2 (gensym key)])
-          ;; e is gen 1, key2 is gen 0:
-          (set-car! e key2)
-          (collect 1 1 2)
-          ;; Now, e is gen 1, key2 is gen 0
-          (and (eq? (car e) key2)
-               (begin
-                 (collect 1 2 2)
-                 ;; Check that the GC update the reference to `key2` in `e`:
-                 (eq? (car e) key2)))))))
+   (with-interrupts-disabled
+    (parameterize ([#%$enable-check-heap #t])
+      (let ([key "key"])
+        (let ([e (ephemeron-cons key #f)])
+          (collect 0 1 1)
+          (let ([key2 (gensym key)])
+            ;; e is gen 1, key2 is gen 0:
+            (set-car! e key2)
+            (collect 1 1 2)
+            ;; Now, e is gen 1, key2 is gen 0
+            (and (eq? (car e) key2)
+                 (begin
+                   (collect 1 2 2)
+                   ;; Check that the GC update the reference to `key2` in `e`:
+                   (eq? (car e) key2))))))))
 
    ;; ----------------------------------------
    ;; Check fasl: