diff --git a/fastgit/core.py b/fastgit/core.py
index 84eec35..c5fc0d9 100644
--- a/fastgit/core.py
+++ b/fastgit/core.py
@@ -31,10 +31,12 @@ def __init__(self, d): self.d = Path(d)
 
     def __call__(self, cmd, *args, split=None, mute_errors=False, **kwargs):
         args = listify(args)
-        args += concat((f'-{k}',v) for k,v in kwargs.items() if len(k)==1)
-        args += [f'--{k}={v}' for k,v in kwargs.items() if len(k)>1]
+        args += concat((f'-{k}',v) for k,v in kwargs.items() if len(k)==1 and v is not True)
+        args += [f'-{k}' for k,v in kwargs.items() if len(k)==1 and v is True]
+        args += [f'--{k.replace("_","-")}={v}' for k,v in kwargs.items() if len(k)>1 and v is not True and v is not False]
+        args += [f'--{k.replace("_","-")}' for k,v in kwargs.items() if len(k)>1 and v is True]
         try: return callgit(self.d, cmd, *args, split=split)
-        except CalledProcessError as e: 
+        except CalledProcessError as e:
             if not mute_errors: print(f'ERROR: Git.__call__ caught exception {e} \n with stderr={e.stderr}')
 
     def __getattr__(self, nm):
diff --git a/nbs/00_core.ipynb b/nbs/00_core.ipynb
index b4ca3e2..85d4e55 100644
--- a/nbs/00_core.ipynb
+++ b/nbs/00_core.ipynb
@@ -112,28 +112,7 @@
    "id": "97f78839",
    "metadata": {},
    "outputs": [],
-   "source": [
-    "#| export\n",
-    "class Git:\n",
-    "    def __init__(self, d): self.d = Path(d)\n",
-    "\n",
-    "    def __call__(self, cmd, *args, split=None, mute_errors=False, **kwargs):\n",
-    "        args = listify(args)\n",
-    "        args += concat((f'-{k}',v) for k,v in kwargs.items() if len(k)==1)\n",
-    "        args += [f'--{k}={v}' for k,v in kwargs.items() if len(k)>1]\n",
-    "        try: return callgit(self.d, cmd, *args, split=split)\n",
-    "        except CalledProcessError as e: \n",
-    "            if not mute_errors: print(f'ERROR: Git.__call__ caught exception {e} \\n with stderr={e.stderr}')\n",
-    "\n",
-    "    def __getattr__(self, nm):\n",
-    "        if nm.startswith('_'): raise AttributeError(nm)\n",
-    "        return partial(self, nm.replace('_','-'))\n",
-    "\n",
-    "    def top(self): return self.rev_parse('--show-toplevel', mute_errors=True)\n",
-    "    \n",
-    "    @property\n",
-    "    def exists(self): return self.top() is not None"
-   ]
+   "source": "#| export\nclass Git:\n    def __init__(self, d): self.d = Path(d)\n\n    def __call__(self, cmd, *args, split=None, mute_errors=False, **kwargs):\n        args = listify(args)\n        args += concat((f'-{k}',v) for k,v in kwargs.items() if len(k)==1 and v is not True)\n        args += [f'-{k}' for k,v in kwargs.items() if len(k)==1 and v is True]\n        args += [f'--{k.replace(\"_\",\"-\")}={v}' for k,v in kwargs.items() if len(k)>1 and v is not True and v is not False]\n        args += [f'--{k.replace(\"_\",\"-\")}' for k,v in kwargs.items() if len(k)>1 and v is True]\n        try: return callgit(self.d, cmd, *args, split=split)\n        except CalledProcessError as e:\n            if not mute_errors: print(f'ERROR: Git.__call__ caught exception {e} \\n with stderr={e.stderr}')\n\n    def __getattr__(self, nm):\n        if nm.startswith('_'): raise AttributeError(nm)\n        return partial(self, nm.replace('_','-'))\n\n    def top(self): return self.rev_parse('--show-toplevel', mute_errors=True)\n    \n    @property\n    def exists(self): return self.top() is not None"
   },
   {
    "cell_type": "code",
@@ -185,4 +164,4 @@
  "metadata": {},
  "nbformat": 4,
  "nbformat_minor": 5
-}
+}
\ No newline at end of file