diff --git a/sphinx/builders/__init__.py b/sphinx/builders/__init__.py
index bb02058f7bf..4871f4603c8 100644
--- a/sphinx/builders/__init__.py
+++ b/sphinx/builders/__init__.py
@@ -15,7 +15,7 @@
 
 from sphinx.config import Config
 from sphinx.deprecation import RemovedInSphinx70Warning
-from sphinx.environment import CONFIG_CHANGED_REASON, CONFIG_OK, BuildEnvironment
+from sphinx.environment import CONFIG_CHANGED_REASON, CONFIG_OK, BuildEnvironment, _safe_mtime
 from sphinx.environment.adapters.asset import ImageAdapter
 from sphinx.errors import SphinxError
 from sphinx.events import EventManager
@@ -512,11 +512,7 @@ def read_doc(self, docname: str) -> None:
             doctree = publisher.document
 
         # store time of reading, for outdated files detection
-        # (Some filesystems have coarse timestamp resolution;
-        # therefore time.time() can be older than filesystem's timestamp.
-        # For example, FAT32 has 2sec timestamp resolution.)
-        self.env.all_docs[docname] = max(time.time(),
-                                         path.getmtime(self.env.doc2path(docname)))
+        self.env.all_docs[docname] = _safe_mtime(self.env.doc2path(docname))
 
         # cleanup
         self.env.temp_data.clear()
diff --git a/sphinx/environment/__init__.py b/sphinx/environment/__init__.py
index e6f1e162179..979f13935ff 100644
--- a/sphinx/environment/__init__.py
+++ b/sphinx/environment/__init__.py
@@ -9,6 +9,7 @@
 from copy import copy
 from datetime import datetime
 from os import path
+import time
 from typing import TYPE_CHECKING, Any, Callable, Generator, Iterator
 
 from docutils import nodes
@@ -172,6 +173,9 @@ def __init__(self, app: Sphinx):
         # docname -> set of dependent file
         # names, relative to documentation root
         self.dependencies: dict[str, set[str]] = defaultdict(set)
+        # dependent file -> mtime at the time of reading
+        # contains all dependent files
+        self.all_dependencies: dict[str, float] = {}
         # docname -> set of included file
         # docnames included from other documents
         self.included: dict[str, set[str]] = defaultdict(set)
@@ -447,6 +451,7 @@ def find_files(self, config: Config, builder: Builder) -> None:
                     domain = docname_to_domain(docname, self.config.gettext_compact)
                     if domain in mo_paths:
                         self.dependencies[docname].add(mo_paths[domain])
+                        self.all_dependencies[mo_paths[domain]] = _safe_mtime(mo_paths[domain])
         except OSError as exc:
             raise DocumentError(__('Failed to scan documents in %s: %r') %
                                 (self.srcdir, exc)) from exc
@@ -502,19 +507,24 @@ def get_outdated_files(self, config_changed: bool) -> tuple[set[str], set[str],
                                 deppath)
                             changed.add(docname)
                             break
-                        depmtime = path.getmtime(deppath)
-                        if depmtime > mtime:
+                        depmtime = self.all_dependencies[dep]
+                        newdepmtime = path.getmtime(deppath)
+                        if newdepmtime > depmtime:
                             try:
-                                depmtime_dt = datetime.utcfromtimestamp(depmtime)
+                                newdepmtime_dt = datetime.utcfromtimestamp(newdepmtime)
                             except ValueError:  # e.g., year 53606865 is out of range
+                                newdepmtime_dt = depmtime
+                            try:
+                                depmtime_dt = datetime.utcfromtimestamp(depmtime)
+                            except ValueError:
                                 depmtime_dt = depmtime
                             logger.debug(
                                 '[build target] outdated %r '
                                 'from dependency %r: %s -> %s',
                                 docname,
                                 deppath,
-                                datetime.utcfromtimestamp(mtime),
-                                depmtime_dt)
+                                depmtime_dt,
+                                newdepmtime_dt)
                             changed.add(docname)
                             break
                     except OSError:
@@ -567,6 +577,7 @@ def note_dependency(self, filename: str) -> None:
         *filename* should be absolute or relative to the source directory.
         """
         self.dependencies[self.docname].add(filename)
+        self.all_dependencies[filename] = path.getmtime(filename)
 
     def note_included(self, filename: str) -> None:
         """Add *filename* as a included from other document.
@@ -744,3 +755,10 @@ def check_consistency(self) -> None:
         for domain in self.domains.values():
             domain.check_consistency()
         self.events.emit('env-check-consistency', self)
+
+
+def _safe_mtime(fname):
+    # (Some filesystems have coarse timestamp resolution;
+    # therefore time.time() can be older than filesystem's timestamp.
+    # For example, FAT32 has 2sec timestamp resolution.)
+    return max(time.time(), path.getmtime(fname))