diff --git a/nibabel/analyze.py b/nibabel/analyze.py
index dc352505c6..a5ff79d83b 100644
--- a/nibabel/analyze.py
+++ b/nibabel/analyze.py
@@ -95,7 +95,6 @@
 from .fileholders import copy_file_map
 from .batteryrunners import Report
 from .arrayproxy import ArrayProxy
-from .keywordonly import kw_only_meth
 
 # Sub-parts of standard analyze header from
 # Mayo dbh.h file
@@ -933,8 +932,7 @@ def set_data_dtype(self, dtype):
         self._header.set_data_dtype(dtype)
 
     @classmethod
-    @kw_only_meth(1)
-    def from_file_map(klass, file_map, mmap=True, keep_file_open=None):
+    def from_file_map(klass, file_map, *, mmap=True, keep_file_open=None):
         ''' Class method to create image from mapping in ``file_map``
 
         .. deprecated:: 2.4.1
diff --git a/nibabel/arrayproxy.py b/nibabel/arrayproxy.py
index b8313e8ae4..5852191968 100644
--- a/nibabel/arrayproxy.py
+++ b/nibabel/arrayproxy.py
@@ -34,7 +34,6 @@
 from .deprecated import deprecate_with_version
 from .volumeutils import array_from_file, apply_read_scaling
 from .fileslice import fileslice, canonical_slicers
-from .keywordonly import kw_only_meth
 from . import openers
 
 
@@ -96,8 +95,7 @@ class ArrayProxy(object):
     order = 'F'
     _header = None
 
-    @kw_only_meth(2)
-    def __init__(self, file_like, spec, mmap=True, keep_file_open=None):
+    def __init__(self, file_like, spec, *, mmap=True, keep_file_open=None):
         """Initialize array proxy instance
 
         .. deprecated:: 2.4.1
diff --git a/nibabel/brikhead.py b/nibabel/brikhead.py
index 7ef1386872..7e34c36b36 100644
--- a/nibabel/brikhead.py
+++ b/nibabel/brikhead.py
@@ -36,7 +36,6 @@
 
 from .arrayproxy import ArrayProxy
 from .fileslice import strided_scalar
-from .keywordonly import kw_only_meth
 from .spatialimages import (
     SpatialImage,
     SpatialHeader,
@@ -220,8 +219,7 @@ class AFNIArrayProxy(ArrayProxy):
         None
     """
 
-    @kw_only_meth(2)
-    def __init__(self, file_like, header, mmap=True, keep_file_open=None):
+    def __init__(self, file_like, header, *, mmap=True, keep_file_open=None):
         """
         Initialize AFNI array proxy
 
@@ -504,8 +502,7 @@ class AFNIImage(SpatialImage):
     ImageArrayProxy = AFNIArrayProxy
 
     @classmethod
-    @kw_only_meth(1)
-    def from_file_map(klass, file_map, mmap=True, keep_file_open=None):
+    def from_file_map(klass, file_map, *, mmap=True, keep_file_open=None):
         """
         Creates an AFNIImage instance from `file_map`
 
diff --git a/nibabel/cifti2/cifti2.py b/nibabel/cifti2/cifti2.py
index 1a5307eba5..a19a04a02f 100644
--- a/nibabel/cifti2/cifti2.py
+++ b/nibabel/cifti2/cifti2.py
@@ -24,7 +24,6 @@
 from ..dataobj_images import DataobjImage
 from ..nifti2 import Nifti2Image, Nifti2Header
 from ..arrayproxy import reshape_dataobj
-from ..keywordonly import kw_only_meth
 from warnings import warn
 
 
@@ -1389,8 +1388,7 @@ def nifti_header(self):
         return self._nifti_header
 
     @classmethod
-    @kw_only_meth(1)
-    def from_file_map(klass, file_map, mmap=True, keep_file_open=None):
+    def from_file_map(klass, file_map, *, mmap=True, keep_file_open=None):
         """ Load a CIFTI-2 image from a file_map
 
         Parameters
diff --git a/nibabel/dataobj_images.py b/nibabel/dataobj_images.py
index dd4c853537..bc8ef07f03 100644
--- a/nibabel/dataobj_images.py
+++ b/nibabel/dataobj_images.py
@@ -12,7 +12,6 @@
 
 from .arrayproxy import is_proxy
 from .filebasedimages import FileBasedImage
-from .keywordonly import kw_only_meth
 from .deprecated import deprecate_with_version
 
 
@@ -420,8 +419,7 @@ def get_shape(self):
         return self.shape
 
     @classmethod
-    @kw_only_meth(1)
-    def from_file_map(klass, file_map, mmap=True, keep_file_open=None):
+    def from_file_map(klass, file_map, *, mmap=True, keep_file_open=None):
         ''' Class method to create image from mapping in ``file_map``
 
         .. deprecated:: 2.4.1
@@ -458,8 +456,7 @@ def from_file_map(klass, file_map, mmap=True, keep_file_open=None):
         raise NotImplementedError
 
     @classmethod
-    @kw_only_meth(1)
-    def from_filename(klass, filename, mmap=True, keep_file_open=None):
+    def from_filename(klass, filename, *, mmap=True, keep_file_open=None):
         '''Class method to create image from filename `filename`
 
         .. deprecated:: 2.4.1
diff --git a/nibabel/ecat.py b/nibabel/ecat.py
index a0923f0753..4a2b55551f 100644
--- a/nibabel/ecat.py
+++ b/nibabel/ecat.py
@@ -54,7 +54,6 @@
 from .arraywriters import make_array_writer
 from .wrapstruct import WrapStruct
 from .fileslice import canonical_slicers, predict_shape, slice2outax
-from .keywordonly import kw_only_meth
 from .deprecated import deprecate_with_version
 
 BLOCK_SIZE = 512
@@ -901,8 +900,7 @@ def _get_fileholders(file_map):
         return file_map['header'], file_map['image']
 
     @classmethod
-    @kw_only_meth(1)
-    def from_file_map(klass, file_map, mmap=True, keep_file_open=None):
+    def from_file_map(klass, file_map, *, mmap=True, keep_file_open=None):
         """class method to create image from mapping
         specified in file_map
         """
diff --git a/nibabel/freesurfer/mghformat.py b/nibabel/freesurfer/mghformat.py
index 6eb0f156e9..8324c112e0 100644
--- a/nibabel/freesurfer/mghformat.py
+++ b/nibabel/freesurfer/mghformat.py
@@ -21,7 +21,6 @@
 from ..spatialimages import HeaderDataError, SpatialImage
 from ..fileholders import FileHolder
 from ..arrayproxy import ArrayProxy, reshape_dataobj
-from ..keywordonly import kw_only_meth
 from ..openers import ImageOpener
 from ..batteryrunners import BatteryRunner, Report
 from ..wrapstruct import LabeledWrapStruct
@@ -537,8 +536,7 @@ def filespec_to_file_map(klass, filespec):
         return super(MGHImage, klass).filespec_to_file_map(filespec)
 
     @classmethod
-    @kw_only_meth(1)
-    def from_file_map(klass, file_map, mmap=True, keep_file_open=None):
+    def from_file_map(klass, file_map, *, mmap=True, keep_file_open=None):
         ''' Class method to create image from mapping in ``file_map``
 
         .. deprecated:: 2.4.1
diff --git a/nibabel/keywordonly.py b/nibabel/keywordonly.py
index 8cb4908c1e..198e70f2c9 100644
--- a/nibabel/keywordonly.py
+++ b/nibabel/keywordonly.py
@@ -2,6 +2,13 @@
 """
 
 from functools import wraps
+import warnings
+
+warnings.warn("We will remove this module from nibabel 5.0. "
+              "Please use the built-in Python `*` argument to ensure "
+              "keyword-only parameters (see PEP 3102).",
+              DeprecationWarning,
+              stacklevel=2)
 
 
 def kw_only_func(n):
diff --git a/nibabel/minc1.py b/nibabel/minc1.py
index c41af5c454..a4c1f3c832 100644
--- a/nibabel/minc1.py
+++ b/nibabel/minc1.py
@@ -17,7 +17,6 @@
 from .spatialimages import SpatialHeader, SpatialImage
 from .fileslice import canonical_slicers
 
-from .keywordonly import kw_only_meth
 from .deprecated import deprecate_with_version
 
 _dt_dict = {
@@ -340,8 +339,7 @@ class Minc1Image(SpatialImage):
     ImageArrayProxy = MincImageArrayProxy
 
     @classmethod
-    @kw_only_meth(1)
-    def from_file_map(klass, file_map, mmap=True, keep_file_open=None):
+    def from_file_map(klass, file_map, *, mmap=True, keep_file_open=None):
         # Note that mmap and keep_file_open are included for proper
         with file_map['image'].get_prepare_fileobj() as fobj:
             minc_file = Minc1File(netcdf_file(fobj))
diff --git a/nibabel/minc2.py b/nibabel/minc2.py
index b27d43f77f..a73114081c 100644
--- a/nibabel/minc2.py
+++ b/nibabel/minc2.py
@@ -27,7 +27,6 @@
 """
 import numpy as np
 
-from .keywordonly import kw_only_meth
 from ._h5py_compat import h5py
 
 from .minc1 import Minc1File, MincHeader, Minc1Image, MincError
@@ -158,8 +157,7 @@ class Minc2Image(Minc1Image):
     header_class = Minc2Header
 
     @classmethod
-    @kw_only_meth(1)
-    def from_file_map(klass, file_map, mmap=True, keep_file_open=None):
+    def from_file_map(klass, file_map, *, mmap=True, keep_file_open=None):
         holder = file_map['image']
         if holder.filename is None:
             raise MincError('MINC2 needs filename for load')
diff --git a/nibabel/parrec.py b/nibabel/parrec.py
index 59eac79809..98ae00587f 100644
--- a/nibabel/parrec.py
+++ b/nibabel/parrec.py
@@ -130,7 +130,6 @@
 from locale import getpreferredencoding
 from collections import OrderedDict
 
-from .keywordonly import kw_only_meth
 from .spatialimages import SpatialHeader, SpatialImage
 from .eulerangles import euler2mat
 from .volumeutils import Recoder, array_from_file
@@ -584,8 +583,7 @@ def exts2pars(exts_source):
 
 class PARRECArrayProxy(object):
 
-    @kw_only_meth(2)
-    def __init__(self, file_like, header, mmap=True, scaling='dv'):
+    def __init__(self, file_like, header, *, mmap=True, scaling='dv'):
         """ Initialize PARREC array proxy
 
         Parameters
@@ -1277,8 +1275,7 @@ class PARRECImage(SpatialImage):
     ImageArrayProxy = PARRECArrayProxy
 
     @classmethod
-    @kw_only_meth(1)
-    def from_file_map(klass, file_map, mmap=True, permit_truncated=False,
+    def from_file_map(klass, file_map, *, mmap=True, permit_truncated=False,
                       scaling='dv', strict_sort=False):
         """ Create PARREC image from file map `file_map`
 
@@ -1318,8 +1315,7 @@ def from_file_map(klass, file_map, mmap=True, permit_truncated=False,
                      file_map=file_map)
 
     @classmethod
-    @kw_only_meth(1)
-    def from_filename(klass, filename, mmap=True, permit_truncated=False,
+    def from_filename(klass, filename, *, mmap=True, permit_truncated=False,
                       scaling='dv', strict_sort=False):
         """ Create PARREC image from filename `filename`
 
diff --git a/nibabel/spm99analyze.py b/nibabel/spm99analyze.py
index d420bb0c2e..09b857ba32 100644
--- a/nibabel/spm99analyze.py
+++ b/nibabel/spm99analyze.py
@@ -16,7 +16,6 @@
 
 from .batteryrunners import Report
 from . import analyze  # module import
-from .keywordonly import kw_only_meth
 from .optpkg import optional_package
 have_scipy = optional_package('scipy')[1]
 
@@ -244,8 +243,7 @@ class Spm99AnalyzeImage(analyze.AnalyzeImage):
     rw = have_scipy
 
     @classmethod
-    @kw_only_meth(1)
-    def from_file_map(klass, file_map, mmap=True, keep_file_open=None):
+    def from_file_map(klass, file_map, *, mmap=True, keep_file_open=None):
         ''' Class method to create image from mapping in ``file_map``
 
         .. deprecated:: 2.4.1
diff --git a/nibabel/tests/test_removalschedule.py b/nibabel/tests/test_removalschedule.py
index ce1ba668b2..a0c3484a3a 100644
--- a/nibabel/tests/test_removalschedule.py
+++ b/nibabel/tests/test_removalschedule.py
@@ -2,6 +2,7 @@
 from ..testing import assert_raises, assert_false
 
 MODULE_SCHEDULE = [
+    ('5.0.0', ['nibabel.keywordonly']),
     ('4.0.0', ['nibabel.trackvis']),
     ('3.0.0', ['nibabel.minc', 'nibabel.checkwarns']),
     # Verify that the test will be quiet if the schedule outlives the modules