diff --git a/API.md b/API.md
index 7469eec..4e15298 100644
--- a/API.md
+++ b/API.md
@@ -144,13 +144,13 @@ from jaxtyping import install_import_hook
 # Plus any one of the following:
 
 # decorate @jaxtyped and @typeguard.typechecked
-with install_import_hook("foo", ("typeguard", "typechecked")):
+with install_import_hook("foo", "typeguard.typechecked"):
     import foo          # Any module imported inside this `with` block, whose name begins
     import foo.bar      # with the specified string, will automatically have both `@jaxtyped`
     import foo.bar.qux  # and the specified typechecker applied to all of their functions.
 
 # decorate @jaxtyped and @beartype.beartype
-with install_import_hook("foo", ("beartype", "beartype")):
+with install_import_hook("foo", "beartype.beartype"):
     ...
     
 # decorate only @jaxtyped (if you want that for some reason)
@@ -177,7 +177,7 @@ The import hook will automatically decorate all functions, and the `__init__` me
 ```python
 ### entry_point.py
 from jaxtyping import install_import_hook
-with install_import_hook("do_stuff", ("typeguard", "typechecked")):
+with install_import_hook("do_stuff", "typeguard.typechecked"):
     import do_stuff
 
 ### do_stuff.py
@@ -192,7 +192,7 @@ def g(x: Float32[Array, "..."]):
 ```python
 ### __init__.py
 from jaxtyping import install_import_hook
-with install_import_hook("my_library_name", ("beartype", "beartype")):
+with install_import_hook("my_library_name", "beartype.beartype"):
     from .subpackage import foo  # full name is my_library_name.subpackage so will be hook'd
     from .another_subpackage import bar  # full name is my_library_name.another_subpackage so will be hook'd.
 ```
diff --git a/jaxtyping/import_hook.py b/jaxtyping/import_hook.py
index 070817e..ed3690f 100644
--- a/jaxtyping/import_hook.py
+++ b/jaxtyping/import_hook.py
@@ -55,7 +55,7 @@ from importlib.abc import MetaPathFinder
 from importlib.machinery import SourceFileLoader
 from importlib.util import cache_from_source, decode_source
 from inspect import isclass
-from typing import Iterable, List, Optional, Tuple
+from typing import Iterable, List, Optional, Tuple, Union
 from unittest.mock import patch
 
 
@@ -70,7 +70,8 @@ def _optimized_cache_from_source(path, debug_override=None):
     # Version 3: now also annotating classes.
     # Version 4: I'm honestly not sure, but bumping this fixed some kind of odd error.
     #     Maybe I changed something with hte classes part way through version 3?
-    return cache_from_source(path, debug_override, optimization="jaxtyping4")
+    # Version 5: Added support for string-based `typechecker` argument.
+    return cache_from_source(path, debug_override, optimization="jaxtyping5")
 
 
 def _dot_lookup(*elements):
@@ -80,6 +81,12 @@ def _dot_lookup(*elements):
     return out
 
 
+def _str_lookup(string):
+    module = ast.parse(string)
+    (expr,) = module.body
+    return expr.value
+
+
 class _JaxtypingTransformer(ast.NodeVisitor):
     def __init__(self, *, typechecker) -> None:
         self._parents: List[ast.AST] = []
@@ -96,7 +103,7 @@ class _JaxtypingTransformer(ast.NodeVisitor):
             else:
                 node.body.insert(i, ast.Import(names=[ast.alias("jaxtyping", None)]))
                 if self._typechecker is not None:
-                    typechecker_module, _ = self._typechecker
+                    typechecker_module, _ = self._typechecker.split(".", 1)
                     node.body.insert(
                         i, ast.Import(names=[ast.alias(typechecker_module, None)])
                     )
@@ -112,7 +119,7 @@ class _JaxtypingTransformer(ast.NodeVisitor):
         if self._typechecker is None:
             args = [ast.Constant(None)]
         else:
-            args = [_dot_lookup(*self._typechecker)]
+            args = [_str_lookup(self._typechecker)]
         node.decorator_list.insert(0, ast.Call(func, args, keywords=[]))
         self._parents.append(node)
         self.generic_visit(node)
@@ -137,7 +144,7 @@ class _JaxtypingTransformer(ast.NodeVisitor):
                 # Place at the end of the decorator list, as decorators
                 # frequently remove annotations from functions and we'd like to
                 # use those annotations.
-                node.decorator_list.append(_dot_lookup(*self._typechecker))
+                node.decorator_list.append(_str_lookup(self._typechecker))
         self._parents.append(node)
         self.generic_visit(node)
         self._parents.pop()
@@ -234,7 +241,7 @@ class ImportHookManager:
 # Deliberately no default for `typechecker` so that folks must opt-in to not having
 # a typechecker.
 def install_import_hook(
-    modules: Iterable[str], typechecker: Optional[Tuple[str, str]]
+    modules: Iterable[str], typechecker: Optional[Union[str, Tuple[str, str]]]
 ) -> ImportHookManager:
     """Automatically apply `@jaxtyped`, and optionally a type checker, to all classes
     and functions.
@@ -246,9 +253,9 @@ def install_import_hook(
     - `packages`: the names of the modules in which to automatically apply `@jaxtyped`
         and `@typechecked`.
     - `typechecker`: the module and function of the typechecker you want to use, as a
-        2-tuple of strings. For example `typechecker=("typeguard", "typechecked")` or
-        `typechecker=("beartype", "beartype")`. You may pass `typechecker=None` if you
-        do not want to automatically decorate with a typechecker as well.
+        string. For example `typechecker="typeguard.typechecked"`, or
+        `typechecker="beartype.beartype"`. You may pass `typechecker=None` if you do not
+        want to automatically decorate with a typechecker as well.
 
     If the function already has any decorators on it, then both the `@jaxtyped` and the
     typechecker decorators will go at the bottom of the decorator list, e.g.
@@ -286,6 +293,10 @@ def install_import_hook(
     if isinstance(modules, str):
         modules = [modules]
 
+    # Support old less-flexible API.
+    if isinstance(typechecker, tuple):
+        typechecker = ".".join(typechecker)
+
     for i, finder in enumerate(sys.meta_path):
         if (
             isclass(finder)
diff --git a/test/import_hook_tester_beartype_full.py b/test/import_hook_tester_beartype_full.py
new file mode 100644
index 0000000..b77b756
--- /dev/null
+++ b/test/import_hook_tester_beartype_full.py
@@ -0,0 +1,62 @@
+# Copyright (c) 2022 Google LLC
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy of
+# this software and associated documentation files (the "Software"), to deal in
+# the Software without restriction, including without limitation the rights to
+# use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+# the Software, and to permit persons to whom the Software is furnished to do so,
+# subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+# FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+# COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+# IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+import dataclasses
+
+import equinox as eqx
+import jax.numpy as jnp
+import pytest
+
+from jaxtyping import Float32
+
+from .helpers import ParamError
+
+
+def g(x: Float32[jnp.ndarray, " b"]):
+    pass
+
+
+g(jnp.array([1.0]))
+with pytest.raises(ParamError):
+    g(jnp.array(1))
+
+
+class M(eqx.Module):
+    foo: int
+    bar: Float32[jnp.ndarray, " a"]
+
+
+M(1, jnp.array([1.0]))
+with pytest.raises(ParamError):
+    M(1.0, jnp.array([1.0]))
+with pytest.raises(ParamError):
+    M(1, jnp.array(1.0))
+
+
+@dataclasses.dataclass
+class D:
+    foo: int
+    bar: Float32[jnp.ndarray, " a"]
+
+
+D(1, jnp.array([1.0]))
+with pytest.raises(ParamError):
+    D(1.0, jnp.array([1.0]))
+with pytest.raises(ParamError):
+    D(1, jnp.array(1.0))
diff --git a/test/import_hook_tester_beartype_old.py b/test/import_hook_tester_beartype_old.py
new file mode 100644
index 0000000..b77b756
--- /dev/null
+++ b/test/import_hook_tester_beartype_old.py
@@ -0,0 +1,62 @@
+# Copyright (c) 2022 Google LLC
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy of
+# this software and associated documentation files (the "Software"), to deal in
+# the Software without restriction, including without limitation the rights to
+# use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+# the Software, and to permit persons to whom the Software is furnished to do so,
+# subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+# FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+# COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+# IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+import dataclasses
+
+import equinox as eqx
+import jax.numpy as jnp
+import pytest
+
+from jaxtyping import Float32
+
+from .helpers import ParamError
+
+
+def g(x: Float32[jnp.ndarray, " b"]):
+    pass
+
+
+g(jnp.array([1.0]))
+with pytest.raises(ParamError):
+    g(jnp.array(1))
+
+
+class M(eqx.Module):
+    foo: int
+    bar: Float32[jnp.ndarray, " a"]
+
+
+M(1, jnp.array([1.0]))
+with pytest.raises(ParamError):
+    M(1.0, jnp.array([1.0]))
+with pytest.raises(ParamError):
+    M(1, jnp.array(1.0))
+
+
+@dataclasses.dataclass
+class D:
+    foo: int
+    bar: Float32[jnp.ndarray, " a"]
+
+
+D(1, jnp.array([1.0]))
+with pytest.raises(ParamError):
+    D(1.0, jnp.array([1.0]))
+with pytest.raises(ParamError):
+    D(1, jnp.array(1.0))
diff --git a/test/import_hook_tester_typeguard_old.py b/test/import_hook_tester_typeguard_old.py
new file mode 100644
index 0000000..b77b756
--- /dev/null
+++ b/test/import_hook_tester_typeguard_old.py
@@ -0,0 +1,62 @@
+# Copyright (c) 2022 Google LLC
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy of
+# this software and associated documentation files (the "Software"), to deal in
+# the Software without restriction, including without limitation the rights to
+# use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+# the Software, and to permit persons to whom the Software is furnished to do so,
+# subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+# FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+# COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+# IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+import dataclasses
+
+import equinox as eqx
+import jax.numpy as jnp
+import pytest
+
+from jaxtyping import Float32
+
+from .helpers import ParamError
+
+
+def g(x: Float32[jnp.ndarray, " b"]):
+    pass
+
+
+g(jnp.array([1.0]))
+with pytest.raises(ParamError):
+    g(jnp.array(1))
+
+
+class M(eqx.Module):
+    foo: int
+    bar: Float32[jnp.ndarray, " a"]
+
+
+M(1, jnp.array([1.0]))
+with pytest.raises(ParamError):
+    M(1.0, jnp.array([1.0]))
+with pytest.raises(ParamError):
+    M(1, jnp.array(1.0))
+
+
+@dataclasses.dataclass
+class D:
+    foo: int
+    bar: Float32[jnp.ndarray, " a"]
+
+
+D(1, jnp.array([1.0]))
+with pytest.raises(ParamError):
+    D(1.0, jnp.array([1.0]))
+with pytest.raises(ParamError):
+    D(1, jnp.array(1.0))
diff --git a/test/test_import_hook.py b/test/test_import_hook.py
index 66c6cc6..9f35fe4 100644
--- a/test/test_import_hook.py
+++ b/test/test_import_hook.py
@@ -22,14 +22,35 @@ import pytest
 from jaxtyping import install_import_hook
 
 
+def test_import_hook_typeguard_old():
+    hook = install_import_hook(
+        "test.import_hook_tester_typeguard_old", ("typeguard", "typechecked")
+    )
+    with hook:
+        from . import import_hook_tester_typeguard_old  # noqa: F401
+
+
 def test_import_hook_typeguard():
     hook = install_import_hook(
-        "test.import_hook_tester_typeguard", ("typeguard", "typechecked")
+        "test.import_hook_tester_typeguard", "typeguard.typechecked"
     )
     with hook:
         from . import import_hook_tester_typeguard  # noqa: F401
 
 
+def test_import_hook_beartype_old():
+    try:
+        import beartype  # noqa: F401
+    except ImportError:
+        pytest.skip("Beartype not installed")
+    else:
+        hook = install_import_hook(
+            "test.import_hook_tester_beartype_old", ("beartype", "beartype")
+        )
+        with hook:
+            from . import import_hook_tester_beartype_old  # noqa: F401
+
+
 def test_import_hook_beartype():
     try:
         import beartype  # noqa: F401
@@ -37,15 +58,27 @@ def test_import_hook_beartype():
         pytest.skip("Beartype not installed")
     else:
         hook = install_import_hook(
-            "test.import_hook_tester_beartype", ("beartype", "beartype")
+            "test.import_hook_tester_beartype", "beartype.beartype"
         )
         with hook:
             from . import import_hook_tester_beartype  # noqa: F401
 
 
+def test_import_hook_beartype_full():
+    try:
+        import beartype  # noqa: F401
+    except ImportError:
+        pytest.skip("Beartype not installed")
+    else:
+        bearchecker = "beartype.beartype(conf=beartype.BeartypeConf(strategy=beartype.BeartypeStrategy.On))"  # noqa: E501
+        hook = install_import_hook("test.import_hook_tester_beartype_full", bearchecker)
+        with hook:
+            from . import import_hook_tester_beartype_full  # noqa: F401
+
+
 def test_import_hook_transitive():
     hook = install_import_hook(
-        "test.import_hook_tester_transitive", ("typeguard", "typechecked")
+        "test.import_hook_tester_transitive", "typeguard.typechecked"
     )
     with hook:
         from . import import_hook_tester_transitive  # noqa: F401
@@ -53,7 +86,7 @@ def test_import_hook_transitive():
 
 def test_import_hook_broken_checker():
     hook = install_import_hook(
-        "test.import_hook_tester_broken_checker", ("jaxtyping", "does_not_exist")
+        "test.import_hook_tester_broken_checker", "jaxtyping.does_not_exist"
     )
     with hook, pytest.raises(AttributeError):
         from . import import_hook_tester_broken_checker  # noqa: F401