diff --git a/spec/spectator/mocks/mock_spec.cr b/spec/spectator/mocks/mock_spec.cr
index eae3a9f..a78b6da 100644
--- a/spec/spectator/mocks/mock_spec.cr
+++ b/spec/spectator/mocks/mock_spec.cr
@@ -404,7 +404,7 @@ Spectator.describe Spectator::Mock do
 
   describe "#inject" do
     context "with a class" do
-      class MockedClass
+      class ::MockedClass
         getter _spectator_invocations = [] of Symbol
 
         getter method1 do
@@ -427,7 +427,7 @@ Spectator.describe Spectator::Mock do
         end
       end
 
-      Spectator::Mock.inject(:class, MockedClass, :mock_name, method1: 123) do
+      Spectator::Mock.inject(:class, ::MockedClass, :mock_name, method1: 123) do
         stub def method2
           :stubbed
         end
@@ -511,7 +511,7 @@ Spectator.describe Spectator::Mock do
     end
 
     context "with a struct" do
-      struct MockedStruct
+      struct ::MockedStruct
         # Using a class variable instead of an instance variable to prevent mutability problems with stub lookup.
         class_getter _spectator_invocations = [] of Symbol
 
@@ -537,7 +537,7 @@ Spectator.describe Spectator::Mock do
         end
       end
 
-      Spectator::Mock.inject(:struct, MockedStruct, :mock_name, method1: 123) do
+      Spectator::Mock.inject(:struct, ::MockedStruct, :mock_name, method1: 123) do
         stub def method2
           :stubbed
         end
@@ -608,7 +608,7 @@ Spectator.describe Spectator::Mock do
     end
 
     context "class method stubs" do
-      class Thing
+      class ::Thing
         def self.foo
           :original
         end
@@ -622,7 +622,7 @@ Spectator.describe Spectator::Mock do
         end
       end
 
-      Spectator::Mock.inject(:class, Thing) do
+      Spectator::Mock.inject(:class, ::Thing) do
         stub def self.foo
           :stub
         end
diff --git a/src/spectator/mocks/mock.cr b/src/spectator/mocks/mock.cr
index b3338d5..174d183 100644
--- a/src/spectator/mocks/mock.cr
+++ b/src/spectator/mocks/mock.cr
@@ -96,6 +96,7 @@ module Spectator
     # The original method functionality will still be accessible, but pass through mock code first.
     # *base* is the keyword for the type being defined - class or struct.
     # *type_name* is the name of the type to inject mock functionality into.
+    # This _must_ be full, resolvable path to the type.
     # An optional *name* of the mock can be provided.
     # Any key-value pairs provided with *value_methods* are used as initial stubs for the mocked type.
     #