diff --git a/commitizen/bump.py b/commitizen/bump.py
index 030c8f1e5..b9e4784ab 100644
--- a/commitizen/bump.py
+++ b/commitizen/bump.py
@@ -82,17 +82,27 @@ def update_version_in_files(
 
     for path, pattern in _resolve_files_and_regexes(version_files, current_version):
         current_version_found = False
+        inconsistent_lines: list[tuple[int, str]] = []
         bumped_lines = []
 
         with open(path, encoding=encoding) as version_file:
-            for line in version_file:
-                bumped_line = (
-                    line.replace(current_version, new_version)
-                    if pattern.search(line)
-                    else line
-                )
-
-                current_version_found = current_version_found or bumped_line != line
+            for lineno, line in enumerate(version_file, 1):
+                if pattern.search(line):
+                    if current_version in line:
+                        bumped_line = line.replace(current_version, new_version)
+                        current_version_found = True
+                    else:
+                        # The version-files regex matched this line, but the
+                        # current version isn't on it. If the line looks like
+                        # it sets a version-shaped value, this is almost
+                        # certainly an inconsistent source we'd otherwise miss
+                        # silently (#595).
+                        bumped_line = line
+                        if check_consistency and _LIKELY_VERSION_VALUE_RE.search(line):
+                            inconsistent_lines.append((lineno, line.rstrip("\r\n")))
+                else:
+                    bumped_line = line
+
                 bumped_lines.append(bumped_line)
 
         if check_consistency and not current_version_found:
@@ -102,6 +112,17 @@ def update_version_in_files(
                 "version_files are possibly inconsistent."
             )
 
+        if check_consistency and inconsistent_lines:
+            details = "\n".join(f"  line {n}: {text}" for n, text in inconsistent_lines)
+            raise CurrentVersionNotFoundError(
+                f"Found line(s) in {path} matching the version regex but "
+                f"holding a version other than {current_version}:\n"
+                f"{details}\n"
+                "This usually means another tool (e.g. poetry, pep621) is "
+                "tracking a different version. Either align them, narrow the "
+                "`version_files` regex, or drop `--check-consistency`."
+            )
+
         bumped_version_file_content = "".join(bumped_lines)
 
         # Write the file out again
@@ -112,6 +133,12 @@ def update_version_in_files(
     return updated_files
 
 
+# Lines that look like ``key = "1.2.3"`` / ``key: 1.2.3-rc.0`` etc. -- enough
+# to catch the typical pyproject.toml ``[tool.poetry].version = "..."`` and
+# ``[project].version = "..."`` cases handled by ``--check-consistency``.
+_LIKELY_VERSION_VALUE_RE = re.compile(r"\d+\.\d+\.\d+(?:[\w.\-+]*)")
+
+
 def _resolve_files_and_regexes(
     patterns: Iterable[str], version: str
 ) -> Generator[tuple[str, re.Pattern], None, None]:
diff --git a/tests/test_bump_update_version_in_files.py b/tests/test_bump_update_version_in_files.py
index 80823a4e1..f25f21ce1 100644
--- a/tests/test_bump_update_version_in_files.py
+++ b/tests/test_bump_update_version_in_files.py
@@ -302,6 +302,61 @@ def test_update_version_in_files_with_check_consistency_true_failure(
     assert expected_msg in str(excinfo.value)
 
 
+def test_update_version_in_files_check_consistency_detects_sibling_version(tmp_path):
+    """Regression test for #595: when a single file's version regex matches
+    multiple version-shaped values (typical pyproject.toml with
+    ``[tool.poetry].version`` and ``[tool.commitizen].version``),
+    ``--check-consistency`` should flag the lines whose version doesn't match
+    the current one instead of silently leaving the sibling out of date.
+    """
+    pyproject = tmp_path / "pyproject.toml"
+    pyproject.write_text(
+        '[tool.poetry]\nversion = "2.5.7"\n\n[tool.commitizen]\nversion = "2.5.2"\n',
+        encoding="utf-8",
+    )
+
+    with pytest.raises(CurrentVersionNotFoundError) as excinfo:
+        bump.update_version_in_files(
+            current_version="2.5.2",
+            new_version="2.6.0",
+            version_files=[f"{pyproject}:version"],
+            check_consistency=True,
+            encoding="utf-8",
+        )
+
+    msg = str(excinfo.value)
+    assert "2.5.7" in msg
+    assert "2.5.2" in msg
+    # The original file must NOT have been rewritten when consistency fails.
+    # (We re-read it to confirm the bump didn't proceed.)
+    assert '"2.5.2"' in pyproject.read_text(encoding="utf-8")
+
+
+def test_update_version_in_files_check_consistency_off_keeps_legacy_behaviour(
+    tmp_path,
+):
+    """Without ``check_consistency``, the old behaviour is preserved: only
+    the lines that contain the current version are updated, and sibling
+    versions are left alone (no exception)."""
+    pyproject = tmp_path / "pyproject.toml"
+    pyproject.write_text(
+        '[tool.poetry]\nversion = "2.5.7"\n\n[tool.commitizen]\nversion = "2.5.2"\n',
+        encoding="utf-8",
+    )
+
+    bump.update_version_in_files(
+        current_version="2.5.2",
+        new_version="2.6.0",
+        version_files=[f"{pyproject}:version"],
+        check_consistency=False,
+        encoding="utf-8",
+    )
+
+    rewritten = pyproject.read_text(encoding="utf-8")
+    assert '[tool.poetry]\nversion = "2.5.7"' in rewritten
+    assert '[tool.commitizen]\nversion = "2.6.0"' in rewritten
+
+
 @pytest.mark.parametrize(
     ("encoding", "filename"),
     [