diff --git a/jedi/api/classes.py b/jedi/api/classes.py
index 8a45488e..e7f7809a 100644
--- a/jedi/api/classes.py
+++ b/jedi/api/classes.py
@@ -531,7 +531,7 @@ class Definition(BaseDefinition):
         typ = self.type
         tree_name = self._name.tree_name
         if typ == 'param':
-            return typ + ' ' + str(self._name)
+            return typ + ' ' + self._name.to_string()
         if typ in ('function', 'class', 'module', 'instance') or tree_name is None:
             if typ == 'function':
                 # For the description we want a short and a pythonic way.
@@ -633,13 +633,14 @@ class CallSignature(Definition):
         return '<%s: index=%r %s>' % (
             type(self).__name__,
             self.index,
-            self._signature,
+            self._signature.to_string(),
         )
 
 
 def _format_signatures(context):
     return '\n'.join(
-        str(signature) for signature in context.get_signatures()
+        signature.to_string()
+        for signature in context.get_signatures()
     )
 
 
diff --git a/jedi/evaluate/compiled/context.py b/jedi/evaluate/compiled/context.py
index e902c575..c5ced978 100644
--- a/jedi/evaluate/compiled/context.py
+++ b/jedi/evaluate/compiled/context.py
@@ -309,7 +309,7 @@ class SignatureParamName(ParamNameInterface, AbstractNameDefinition):
     def string_name(self):
         return self._signature_param.name
 
-    def __str__(self):
+    def to_string(self):
         s = self._kind_string() + self.string_name
         if self._signature_param.has_annotation:
             s += ': ' + self._signature_param.annotation_string
@@ -341,7 +341,7 @@ class UnresolvableParamName(ParamNameInterface, AbstractNameDefinition):
     def get_kind(self):
         return Parameter.POSITIONAL_ONLY
 
-    def __str__(self):
+    def to_string(self):
         string = self.string_name
         if self._default:
             string += '=' + self._default
diff --git a/jedi/evaluate/names.py b/jedi/evaluate/names.py
index c5539664..563506b3 100644
--- a/jedi/evaluate/names.py
+++ b/jedi/evaluate/names.py
@@ -178,7 +178,7 @@ class ParamNameInterface(_ParamMixin):
     def get_kind(self):
         raise NotImplementedError
 
-    def __str__(self):
+    def to_string(self):
         raise NotImplementedError
 
     def get_param(self):
@@ -201,7 +201,7 @@ class BaseTreeParamName(ParamNameInterface, AbstractTreeName):
     annotation_node = None
     default_node = None
 
-    def __str__(self):
+    def to_string(self):
         output = self._kind_string() + self.string_name
         annotation = self.annotation_node
         default = self.default_node
@@ -277,9 +277,6 @@ class ParamNameWrapper(_ParamMixin):
     def __getattr__(self, name):
         return getattr(self._wrapped_param_name, name)
 
-    def __str__(self):
-        return str(self._wrapped_param_name)
-
     def __repr__(self):
         return '<%s: %s>' % (self.__class__.__name__, self._wrapped_param_name)
 
diff --git a/jedi/evaluate/signature.py b/jedi/evaluate/signature.py
index ee832dcc..8e1b2d81 100644
--- a/jedi/evaluate/signature.py
+++ b/jedi/evaluate/signature.py
@@ -2,7 +2,7 @@ from jedi._compatibility import Parameter
 
 
 class _SignatureMixin(object):
-    def __str__(self):
+    def to_string(self):
         def param_strings():
             is_positional = False
             is_kw_only = False
@@ -19,7 +19,7 @@ class _SignatureMixin(object):
                     yield '*'
                     is_kw_only = True
 
-                yield str(n)
+                yield n.to_string()
 
             if is_positional:
                 yield '/'
diff --git a/test/test_evaluate/test_signature.py b/test/test_evaluate/test_signature.py
index 254b5896..76da4fee 100644
--- a/test/test_evaluate/test_signature.py
+++ b/test/test_evaluate/test_signature.py
@@ -33,7 +33,7 @@ def test_compiled_signature(Script, environment, code, sig, names, op, version):
     context, = d._name.infer()
     compiled, = _stub_to_python_context_set(context)
     signature, = compiled.get_signatures()
-    assert str(signature) == sig
+    assert signature.to_string() == sig
     assert [n.string_name for n in signature.get_param_names()] == names
 
 
@@ -90,7 +90,7 @@ def test_tree_signature(Script, environment, code, expected):
         assert not Script(code).call_signatures()
     else:
         sig, = Script(code).call_signatures()
-        assert expected == str(sig._signature)
+        assert expected == sig._signature.to_string()
 
 
 @pytest.mark.parametrize(
@@ -180,7 +180,7 @@ def test_nested_signatures(Script, environment, combination, expected, skip_pre_
     ''')
     code += 'z = ' + combination + '\nz('
     sig, = Script(code).call_signatures()
-    computed = str(sig._signature)
+    computed = sig._signature.to_string()
     if not re.match('\w+\(', expected):
         expected = '<lambda>(' + expected + ')'
     assert expected == computed
@@ -189,7 +189,7 @@ def test_nested_signatures(Script, environment, combination, expected, skip_pre_
 def test_pow_signature(Script):
     # See github #1357
     sigs = Script('pow(').call_signatures()
-    strings = {str(sig._signature) for sig in sigs}
+    strings = {sig._signature.to_string() for sig in sigs}
     assert strings == {'pow(x: float, y: float, z: float, /) -> float',
                        'pow(x: float, y: float, /) -> float',
                        'pow(x: int, y: int, z: int, /) -> Any',
@@ -228,7 +228,7 @@ def test_pow_signature(Script):
 )
 def test_wraps_signature(Script, code, signature, skip_pre_python35):
     sigs = Script(code).call_signatures()
-    assert {str(sig._signature) for sig in sigs} == {signature}
+    assert {sig._signature.to_string() for sig in sigs} == {signature}
 
 
 @pytest.mark.parametrize(