diff --git a/docker/context/context.py b/docker/context/context.py
index 4faf8e701..9d465498a 100644
--- a/docker/context/context.py
+++ b/docker/context/context.py
@@ -175,7 +175,7 @@ def remove(self):
     def __repr__(self):
         return f"<{self.__class__.__name__}: '{self.name}'>"
 
-    def __str__(self):
+    def __str__(self) -> str:
         return json.dumps(self.__call__(), indent=2)
 
     def __call__(self):
diff --git a/docker/errors.py b/docker/errors.py
index d03e10f69..72177f831 100644
--- a/docker/errors.py
+++ b/docker/errors.py
@@ -50,7 +50,7 @@ def __init__(self, message, response=None, explanation=None):
         self.response = response
         self.explanation = explanation
 
-    def __str__(self):
+    def __str__(self) -> str:
         message = super().__str__()
 
         if self.is_client_error():
@@ -121,7 +121,7 @@ class TLSParameterError(DockerException):
     def __init__(self, msg):
         self.msg = msg
 
-    def __str__(self):
+    def __str__(self) -> str:
         return self.msg + (". TLS configurations should map the Docker CLI "
                            "client configurations. See "
                            "https://docs.docker.com/engine/articles/https/ "
@@ -181,7 +181,7 @@ class MissingContextParameter(DockerException):
     def __init__(self, param):
         self.param = param
 
-    def __str__(self):
+    def __str__(self) -> str:
         return (f"missing parameter: {self.param}")
 
 
@@ -189,7 +189,7 @@ class ContextAlreadyExists(DockerException):
     def __init__(self, name):
         self.name = name
 
-    def __str__(self):
+    def __str__(self) -> str:
         return (f"context {self.name} already exists")
 
 
@@ -197,7 +197,7 @@ class ContextException(DockerException):
     def __init__(self, msg):
         self.msg = msg
 
-    def __str__(self):
+    def __str__(self) -> str:
         return (self.msg)
 
 
@@ -205,5 +205,5 @@ class ContextNotFound(DockerException):
     def __init__(self, name):
         self.name = name
 
-    def __str__(self):
+    def __str__(self) -> str:
         return (f"context '{self.name}' not found")
diff --git a/docker/utils/proxy.py b/docker/utils/proxy.py
index e7164b6ce..d0a85637d 100644
--- a/docker/utils/proxy.py
+++ b/docker/utils/proxy.py
@@ -68,7 +68,7 @@ def inject_proxy_environment(self, environment):
         # variables defined in "environment" to take precedence.
         return proxy_env + environment
 
-    def __str__(self):
+    def __str__(self) -> str:
         return (
             'ProxyConfig('
             f'http={self.http}, https={self.https}, '
diff --git a/scripts/versions.py b/scripts/versions.py
index 75e5355eb..360d201af 100755
--- a/scripts/versions.py
+++ b/scripts/versions.py
@@ -51,7 +51,7 @@ def order(self):
 
         return (int(self.major), int(self.minor), int(self.patch)) + stage
 
-    def __str__(self):
+    def __str__(self) -> str:
         stage = f'-{self.stage}' if self.stage else ''
         edition = f'-{self.edition}' if self.edition else ''
         return '.'.join(map(str, self[:3])) + edition + stage