diff --git a/autonerves/fitsable.py b/autonerves/fitsable.py
index 67dc162..16876eb 100644
--- a/autonerves/fitsable.py
+++ b/autonerves/fitsable.py
@@ -9,11 +9,6 @@
     except ImportError:
         pass
 
-try:
-    from astropy.io import fits
-except ImportError:
-    pass
-
 import numpy as np
 from pathlib import Path
 from typing import Dict, Optional, Union, List
@@ -58,8 +53,10 @@ def hdu_list_for_output_from(
         ext_name_list=["data", "noise_map"]
     )
     """
+    from astropy.io import fits
+
     hdu_list = []
-    
+
     header = fits.Header()
 
     if header_dict is not None:
@@ -207,6 +204,8 @@ def ndarray_via_fits_from(
     --------
     array_2d = ndarray_via_fits_from(file_path='/path/to/file/filename.fits', hdu=0)
     """
+    from astropy.io import fits
+
     with fits.open(
         file_path, do_not_scale_image_data=do_not_scale_image_data
     ) as hdu_list:
@@ -235,6 +234,8 @@ def header_obj_from(file_path: Union[Path, str], hdu: int) -> Dict:
     --------
     array_2d = ndarray_via_fits_from(file_path='/path/to/file/filename.fits', hdu=0)
     """
+    from astropy.io import fits
+
     with fits.open(file_path) as hdu_list:
         return hdu_list[hdu].header
 
diff --git a/autonerves/workspace.py b/autonerves/workspace.py
index 2cd621e..34fa932 100644
--- a/autonerves/workspace.py
+++ b/autonerves/workspace.py
@@ -17,6 +17,19 @@ class WorkspaceVersionMismatchError(exc.ConfigException):
 # enough to suggest the clone is genuinely stale.
 _STALENESS_WINDOW_DAYS = 30
 
+# Every library init (autofit, autogalaxy, autolens, ...) calls check_version,
+# so without dedup a byte-identical warning prints once per library in the
+# import chain. Python's own warning registry does not dedupe here because
+# third-party imports between the calls invalidate it.
+_warned_messages = set()
+
+
+def _warn_once(message):
+    if message in _warned_messages:
+        return
+    _warned_messages.add(message)
+    warnings.warn(message)
+
 
 def _read_general_yaml(workspace_root):
     """
@@ -224,7 +237,7 @@ def check_version(library_version, workspace_root=None):
     if floor_version is None or floor_version == "":
         if _is_source_checkout(root):
             return
-        warnings.warn(_missing_version_warning(root, library_version))
+        _warn_once(_missing_version_warning(root, library_version))
         return
 
     if floor_version == library_version:
@@ -234,7 +247,7 @@ def check_version(library_version, workspace_root=None):
     library_parsed = _parse_version(library_version)
 
     if floor_parsed is None or library_parsed is None:
-        warnings.warn(
+        _warn_once(
             _unparseable_mismatch_message(floor_version, library_version, root)
         )
         return
@@ -252,4 +265,4 @@ def check_version(library_version, workspace_root=None):
         and library_date is not None
         and (library_date - floor_date).days > _STALENESS_WINDOW_DAYS
     ):
-        warnings.warn(_stale_workspace_message(floor_version, library_version, root))
+        _warn_once(_stale_workspace_message(floor_version, library_version, root))