diff --git a/Code/GraphMol/Wrap/Atom.cpp b/Code/GraphMol/Wrap/Atom.cpp
index 7b681df61..7832dbbbf 100644
--- a/Code/GraphMol/Wrap/Atom.cpp
+++ b/Code/GraphMol/Wrap/Atom.cpp
@@ -42,18 +42,18 @@ void setQuery(QueryAtom *self, const QueryAtom *other) {
 }
 
 template <class T>
-void AtomSetProp(const Atom *atom, const char *key, const T &val) {
+void AtomSetProp(const Atom *atom, const std::string &key, const T &val) {
   // std::cerr<<"asp: "<<atom<<" " << key<<" - " << val << std::endl;
   atom->setProp<T>(key, val);
 }
 
-int AtomHasProp(const Atom *atom, const char *key) {
+int AtomHasProp(const Atom *atom, const std::string &key) {
   // std::cerr<<"ahp: "<<atom<<" " << key<< std::endl;
   int res = atom->hasProp(key);
   return res;
 }
 
-void AtomClearProp(const Atom *atom, const char *key) {
+void AtomClearProp(const Atom *atom, const std::string &key) {
   if (!atom->hasProp(key)) {
     return;
   }
diff --git a/Code/GraphMol/Wrap/props.hpp b/Code/GraphMol/Wrap/props.hpp
index 058b5eb49..9851c1e58 100644
--- a/Code/GraphMol/Wrap/props.hpp
+++ b/Code/GraphMol/Wrap/props.hpp
@@ -167,11 +167,11 @@ boost::python::dict GetPropsAsDict(const T &obj, bool includePrivate,
 }
 
 template <class RDOb, class T>
-T GetProp(const RDOb *ob, const char *key) {
+T GetProp(const RDOb *ob, const std::string &key) {
   T res;
   try {
     if (!ob->getPropIfPresent(key, res)) {
-      PyErr_SetString(PyExc_KeyError, key);
+      PyErr_SetString(PyExc_KeyError, key.c_str());
       throw python::error_already_set();
     }
     return res;
@@ -203,7 +203,7 @@ template <class RDOb>
 python::object GetPyProp(const RDOb *obj, const std::string &key,
                          bool autoConvert) {
   if (!autoConvert) {
-    return python::object(GetProp<RDOb, std::string>(obj, key.c_str()));
+    return python::object(GetProp<RDOb, std::string>(obj, key));
   } else {
     auto &data = obj->getDict().getData();
     for (auto &rdvalue : data) {
@@ -283,20 +283,20 @@ python::object GetPyProp(const RDOb *obj, const std::string &key,
 }
 
 template <class RDOb>
-int MolHasProp(const RDOb &mol, const char *key) {
+int MolHasProp(const RDOb &mol, const std::string &key) {
   int res = mol.hasProp(key);
   // std::cout << "key: "  << key << ": " << res << std::endl;
   return res;
 }
 
 template <class RDOb, class T>
-void MolSetProp(const RDOb &mol, const char *key, const T &val,
+void MolSetProp(const RDOb &mol, const std::string &key, const T &val,
                 bool computed = false) {
   mol.setProp(key, val, computed);
 }
 
 template <class RDOb>
-void MolClearProp(const RDOb &mol, const char *key) {
+void MolClearProp(const RDOb &mol, const std::string &key) {
   if (!mol.hasProp(key)) {
     return;
   }
diff --git a/Code/GraphMol/Wrap/rdmolfiles.cpp b/Code/GraphMol/Wrap/rdmolfiles.cpp
index 23a8cf433..8c743827e 100644
--- a/Code/GraphMol/Wrap/rdmolfiles.cpp
+++ b/Code/GraphMol/Wrap/rdmolfiles.cpp
@@ -99,7 +99,7 @@ ROMol *MolFromSmarts(python::object ismarts, bool mergeHs,
   }
   return static_cast<ROMol *>(newM);
 }
-ROMol *MolFromTPLFile(const char *filename, bool sanitize = true,
+ROMol *MolFromTPLFile(const std::string &filename, bool sanitize = true,
                       bool skipFirstConf = false) {
   RWMol *newM;
   try {
@@ -126,7 +126,7 @@ ROMol *MolFromTPLBlock(python::object itplBlock, bool sanitize = true,
   return static_cast<ROMol *>(newM);
 }
 
-ROMol *MolFromMolFileHelper(const char *molFilename, bool sanitize,
+ROMol *MolFromMolFileHelper(const std::string &molFilename, bool sanitize,
                             bool removeHs, bool strictParsing) {
   RWMol *newM = nullptr;
   try {
@@ -156,7 +156,7 @@ ROMol *MolFromMolBlock(python::object imolBlock, bool sanitize, bool removeHs,
   return static_cast<ROMol *>(newM);
 }
 
-ROMol *MolFromMolFile(const char *molFilename, bool sanitize, bool removeHs,
+ROMol *MolFromMolFile(const std::string &molFilename, bool sanitize, bool removeHs,
                       bool strictParsing) {
   RWMol *newM = nullptr;
   try {
@@ -171,7 +171,7 @@ ROMol *MolFromMolFile(const char *molFilename, bool sanitize, bool removeHs,
   return static_cast<ROMol *>(newM);
 }
 
-ROMol *MolFromMrvFile(const char *molFilename, bool sanitize, bool removeHs) {
+ROMol *MolFromMrvFile(const std::string &molFilename, bool sanitize, bool removeHs) {
   RWMol *newM = nullptr;
   try {
     newM = MrvFileToMol(molFilename, sanitize, removeHs);
@@ -226,7 +226,7 @@ ROMol *MolFromSVG(python::object imolBlock, bool sanitize, bool removeHs) {
   return static_cast<ROMol *>(res);
 }
 
-ROMol *MolFromMol2File(const char *molFilename, bool sanitize = true,
+ROMol *MolFromMol2File(const std::string &molFilename, bool sanitize = true,
                        bool removeHs = true, bool cleanupSubstructures = true) {
   RWMol *newM;
   try {
@@ -255,7 +255,7 @@ ROMol *MolFromMol2Block(std::string mol2Block, bool sanitize = true,
   return static_cast<ROMol *>(newM);
 }
 
-ROMol *MolFromPDBFile(const char *filename, bool sanitize, bool removeHs,
+ROMol *MolFromPDBFile(const std::string &filename, bool sanitize, bool removeHs,
                       unsigned int flavor, bool proximityBonding) {
   RWMol *newM = nullptr;
   try {
@@ -506,7 +506,7 @@ python::list MolToRandomSmilesHelper(const ROMol &mol, unsigned int numSmiles,
   return pyres;
 }
 
-ROMol *MolFromPNGFile(const char *filename, python::object pyParams) {
+ROMol *MolFromPNGFile(const std::string &filename, python::object pyParams) {
   SmilesParserParams params;
   if (pyParams) {
     params = python::extract<SmilesParserParams>(pyParams);
@@ -604,7 +604,7 @@ python::object addMetadataToPNGStringHelper(python::dict pymetadata,
   return retval;
 }
 
-python::object MolsFromPNGFile(const char *filename, const std::string &tag,
+python::object MolsFromPNGFile(const std::string &filename, const std::string &tag,
                                python::object pyParams) {
   SmilesParserParams params;
   if (pyParams) {
@@ -645,7 +645,7 @@ python::tuple MolsFromPNGString(python::object png, const std::string &tag,
   return python::tuple(res);
 }
 
-python::object MolsFromCDXMLFile(const char *filename, bool sanitize,
+python::object MolsFromCDXMLFile(const std::string &filename, bool sanitize,
                                  bool removeHs) {
   std::vector<std::unique_ptr<RWMol>> mols;
   try {
diff --git a/Code/GraphMol/Wrap/rough_test.py b/Code/GraphMol/Wrap/rough_test.py
index 356530e8f..283426e83 100644
--- a/Code/GraphMol/Wrap/rough_test.py
+++ b/Code/GraphMol/Wrap/rough_test.py
@@ -8252,7 +8252,24 @@ M  END
     chain2mol = Chem.SplitMolByPDBChainId(mol)
     self.assertEqual(len(chain2mol), 1)
     self.assertIn("", chain2mol)
-
+    
+  def testGithub4570(self):
+    # test sending None to get/set prop
+    m = Chem.Mol()
+    # these should not seg fault
+    for func in ["HasProp", "GetProp", "GetIntProp", "GetDoubleProp"]:
+      try:
+        getattr(m, func)(None)
+      except Exception as e:
+        assert "Python argument types" in str(e), f"{func}: {str(e)}"
+    
+    for func, val in [("SetProp", ""), ("SetIntProp", 1), ("SetDoubleProp", 1.0)]:
+      try:
+        getattr(m, func)(None, val)
+      except Exception as e:
+        assert "Python argument types" in str(e), f"{func}: {str(e)}"
+      
+    
 if __name__ == '__main__':
   if "RDTESTCASE" in os.environ:
     suite = unittest.TestSuite()