diff --git a/src/spectator/mocks/exception_stub.cr b/src/spectator/mocks/exception_stub.cr
index 9aee69c..e7b6cb9 100644
--- a/src/spectator/mocks/exception_stub.cr
+++ b/src/spectator/mocks/exception_stub.cr
@@ -20,6 +20,12 @@ module Spectator
     def initialize(method : Symbol, @exception : Exception, constraint : AbstractArguments? = nil, location : Location? = nil)
       super(method, constraint, location)
     end
+
+    # String representation of the stub, formatted as a method call.
+    def to_s(io : IO) : Nil
+      super
+      io << " # raises " << @exception
+    end
   end
 
   module StubModifiers
diff --git a/src/spectator/mocks/typed_stub.cr b/src/spectator/mocks/typed_stub.cr
index 5067215..eabbcb9 100644
--- a/src/spectator/mocks/typed_stub.cr
+++ b/src/spectator/mocks/typed_stub.cr
@@ -9,5 +9,11 @@ module Spectator
   abstract class TypedStub(T) < Stub
     # Invokes the stubbed implementation.
     abstract def call(call : MethodCall) : T
+
+    # String representation of the stub, formatted as a method call.
+    def to_s(io : IO) : Nil
+      super
+      io << " : " << T
+    end
   end
 end
diff --git a/src/spectator/mocks/value_stub.cr b/src/spectator/mocks/value_stub.cr
index 464c38b..7a84d19 100644
--- a/src/spectator/mocks/value_stub.cr
+++ b/src/spectator/mocks/value_stub.cr
@@ -20,6 +20,13 @@ module Spectator
     def initialize(method : Symbol, @value : T, constraint : AbstractArguments? = nil, location : Location? = nil)
       super(method, constraint, location)
     end
+
+    # String representation of the stub, formatted as a method call and return value.
+    def to_s(io : IO) : Nil
+      super
+      io << " # => "
+      @value.inspect(io)
+    end
   end
 
   module StubModifiers