diff --git a/docs/changelog.txt b/docs/changelog.txt
index e51d7c5794..d96475f0ee 100644
--- a/docs/changelog.txt
+++ b/docs/changelog.txt
@@ -59,6 +59,8 @@ Template for new versions:
 ## Fixes
 - Fix mouse clicks bleeding through DFHack windows when clicking in the space between the frame and the window content in resizable windows
 - `autobutcher`: don't run a scanning and marking cycle on the first tick of a fortress to allow for all custom configuration to be set first
+- `nestboxes`: don't consider eggs to be infertile just because the mother has left the nest; eggs can still hatch in this situation
+- `timestream`: adjust the incubation counter on fertile eggs so they hatch at the expected time
 - `logistics`: don't ignore rotten items when applying stockpile logistics operations (e.g. autodump, autoclaim, etc.)
 
 ## Misc Improvements
diff --git a/plugins/nestboxes.cpp b/plugins/nestboxes.cpp
index 6f21628170..64cfcc301b 100644
--- a/plugins/nestboxes.cpp
+++ b/plugins/nestboxes.cpp
@@ -118,15 +118,13 @@ static void do_cycle(color_ostream &out) {
     cycle_timestamp = world->frame_counter;
 
     for (df::building_nest_boxst *nb : world->buildings.other.NEST_BOX) {
-        bool fertile = false;
-        if (nb->claimed_by != -1) {
-            df::unit *u = df::unit::find(nb->claimed_by);
-            if (u && u->pregnancy_timer > 0)
-                fertile = true;
-        }
         for (auto &contained_item : nb->contained_items) {
-            auto *item = virtual_cast<df::item_eggst>(contained_item->item);
-            if (item && item->flags.bits.forbid != fertile) {
+            if (contained_item->use_mode == df::building_item_role_type::PERM)
+                continue;
+            if (auto *item = virtual_cast<df::item_eggst>(contained_item->item)) {
+                bool fertile = item->egg_flags.bits.fertile;
+                if (item->flags.bits.forbid == fertile)
+                    continue;
                 item->flags.bits.forbid = fertile;
                 if (fertile && item->flags.bits.in_job) {
                     // cancel any job involving the egg
@@ -135,7 +133,7 @@ static void do_cycle(color_ostream &out) {
                     if (sref && sref->data.job)
                         Job::removeJob(sref->data.job);
                 }
-                out.print("%d eggs %s.\n", item->getStackSize(), fertile ? "forbidden" : "unforbidden");
+                out.print("nestboxes: %d eggs %s\n", item->getStackSize(), fertile ? "forbidden" : "unforbidden");
             }
         }
     }
diff --git a/plugins/timestream.cpp b/plugins/timestream.cpp
index 0747a30371..512e3c215c 100644
--- a/plugins/timestream.cpp
+++ b/plugins/timestream.cpp
@@ -29,7 +29,9 @@
 #include "df/activity_event_teach_topicst.h"
 #include "df/activity_event_writest.h"
 #include "df/activity_event_worshipst.h"
+#include "df/building_nest_boxst.h"
 #include "df/init.h"
+#include "df/item_eggst.h"
 #include "df/unit.h"
 #include "df/world.h"
 
@@ -571,6 +573,22 @@ static void adjust_activities(color_ostream &out, int32_t timeskip) {
     }
 }
 
+static void adjust_items(color_ostream &out, int32_t timeskip) {
+    // increment incubation counters for fertile eggs in non-forbidden nestboxes
+    for (df::building_nest_boxst *nb : world->buildings.other.NEST_BOX) {
+        for (auto & contained_item : nb->contained_items) {
+            if (contained_item->use_mode == df::building_item_role_type::PERM) {
+                if (contained_item->item->flags.bits.forbid)
+                    break;
+                else
+                    continue;
+            }
+            if (auto *egg = virtual_cast<df::item_eggst>(contained_item->item); egg && egg->egg_flags.bits.fertile)
+                increment_counter(egg, &df::item_eggst::incubation_counter, timeskip);
+        }
+    }
+}
+
 static void do_cycle(color_ostream &out) {
     DEBUG(cycle,out).print("running %s cycle\n", plugin_name);
 
@@ -612,6 +630,7 @@ static void do_cycle(color_ostream &out) {
 
     adjust_units(out, timeskip);
     adjust_activities(out, timeskip);
+    adjust_items(out, timeskip);
 }
 
 /////////////////////////////////////////////////////