diff --git a/tofu/__init__.py b/tofu/__init__.py
index 29c1043d6..d4ba1573e 100644
--- a/tofu/__init__.py
+++ b/tofu/__init__.py
@@ -69,37 +69,39 @@
 import tofu.data as data
 
 
-try:
-    import tofu.imas2tofu as imas2tofu
-    okimas2tofu = True
-except Exception as err:
-    warnings.warn(str(err))
-    okimas2tofu = False
-
-try:
-    import tofu.mag as mag
-    okmag = True
-except Exception as err:
-    warnings.warn(str(err))
-    okmag = False
-
-#import tofu.dust as dust
-
+# -------------------------------------
+#   Try importing optional subpackages
+# -------------------------------------
+
+msg = None
+dsub = dict.fromkeys(['imas2tofu', 'mag'])
+for sub in dsub.keys():
+    try:
+        exec('import tofu.{0} as {0}'.format(sub))
+        dsub[sub] = True
+    except Exception as err:
+        dsub[sub] = str(err)
+
+# -------------------------------------
+# If any error, populate warning and store error message
+# -------------------------------------
+
+lsubout = [sub for sub in dsub.keys() if dsub[sub] is not True]
+if len(lsubout) > 0:
+    lsubout = ['tofu.{0}'.format(ss) for ss in lsubout]
+    msg = "\nThe following subpackages are not available:"
+    msg += "\n    - " + "\n    - ".join(lsubout)
+    msg += "\n  => see tofu.dsub[<subpackage>] for details on error messages"
+    warnings.warn(msg)
+
+# -------------------------------------
+# Add optional subpackages to __all__
+# -------------------------------------
 
 __all__ = ['pathfile','utils','_plot','geom','data']
-if okimas2tofu:
-    __all__.append('imas2tofu')
-if okmag:
-    __all__.append('mag')
-
-
-del sys, warnings, okimas2tofu, okmag
-
-#__all__.extend(['geom', 'mesh', 'matcomp', 'data', 'inv'])
+for sub in dsub.keys():
+    if dsub[sub] is True:
+        __all__.append(sub)
 
-#__name__ = ""
-#__date__ = "$Mar 05, 2014$"
-#__copyright__ = ""
-#__license__ = ""
-#__url__ = ""
-#__path__ =
+# clean-up the mess
+del sys, warnings, lsubout, sub, msg
diff --git a/tofu/imas2tofu/__init__.py b/tofu/imas2tofu/__init__.py
index ea5371cf7..184fc8773 100644
--- a/tofu/imas2tofu/__init__.py
+++ b/tofu/imas2tofu/__init__.py
@@ -19,13 +19,12 @@
         msg += "\n\nIMAS python API issue\n"
         msg += "imas could not be imported into tofu ('import imas' failed):\n"
         msg += "  - it may not be installed (optional dependency)\n"
-        msg += "  - or you not have loaded the good working environment\n\n"
+        msg += "  - or you have loaded the wrong working environment\n\n"
         msg += "    => the optional sub-package tofu.imas2tofu is not usable\n"
     else:
         msg = str(traceback.format_exc())
         msg += "\n\n    => the optional sub-package tofu.imas2tofu is not usable\n"
-    warnings.warn(msg)
-    del msg, err
+    raise Exception(msg)
 
 __all__ = ['MultiIDSLoader', 'load_Config', 'load_Plasma2D',
            'load_Cam', 'load_Data']
diff --git a/tofu/mag/__init__.py b/tofu/mag/__init__.py
index 96b103f5b..ef284347e 100644
--- a/tofu/mag/__init__.py
+++ b/tofu/mag/__init__.py
@@ -7,13 +7,9 @@
 import warnings
 import traceback
 
+msg, err = None, None
 try:
     import imas
-    try:
-        from tofu.mag.magFieldLines import *
-    except Exception:
-        from .magFieldLines import *
-    del warnings, traceback, magFieldLines, mag_ripple
 except Exception as err:
     if str(err) == 'imas not available':
         msg = ""
@@ -25,7 +21,24 @@
     else:
         msg = str(traceback.format_exc())
         msg += "\n\n    => the optional sub-package tofu.mag is not usable\n"
-    warnings.warn(msg)
-    del msg, err
+    raise Exception(msg)
+
+try:
+    import pywed
+except Exception:
+    msg = "pywed not available => no tofu.mag"
+    raise Exception(msg)
+
+try:
+    from tofu.mag.magFieldLines import *
+except Exception:
+    try:
+        from .magFieldLines import *
+    except Exception:
+        msg = "Could not import"
+        raise Exception(msg)
+
+del warnings, traceback, magFieldLines, mag_ripple, pywed, imas
+del msg, err
 
 __all__ = ['MagFieldLines']