diff --git a/lib/mutant/config.rb b/lib/mutant/config.rb
index 871db6777..2791bf155 100644
--- a/lib/mutant/config.rb
+++ b/lib/mutant/config.rb
@@ -24,25 +24,18 @@ class Config
       define_method(:"#{name}?") { public_send(name) }
     end
 
-    boolean = Transform::Boolean.new
-    float   = Transform::Primitive.new(Float)
-    integer = Transform::Primitive.new(Integer)
-    string  = Transform::Primitive.new(String)
-
-    string_array = Transform::Array.new(string)
-
     TRANSFORM = Transform::Sequence.new(
       [
         Transform::Exception.new(SystemCallError, :read.to_proc),
         Transform::Exception.new(YAML::SyntaxError, YAML.method(:safe_load)),
         Transform::Hash.new(
           optional: [
-            Transform::Hash::Key.new('fail_fast',        boolean),
-            Transform::Hash::Key.new('includes',         string_array),
-            Transform::Hash::Key.new('integration',      string),
-            Transform::Hash::Key.new('jobs',             integer),
-            Transform::Hash::Key.new('mutation_timeout', float),
-            Transform::Hash::Key.new('requires',         string_array)
+            Transform::Hash::Key.new('fail_fast',        Transform::BOOLEAN),
+            Transform::Hash::Key.new('includes',         Transform::STRING_ARRAY),
+            Transform::Hash::Key.new('integration',      Transform::STRING),
+            Transform::Hash::Key.new('jobs',             Transform::INTEGER),
+            Transform::Hash::Key.new('mutation_timeout', Transform::FLOAT),
+            Transform::Hash::Key.new('requires',         Transform::STRING_ARRAY)
           ],
           required: []
         ),
diff --git a/lib/mutant/transform.rb b/lib/mutant/transform.rb
index af7e900f3..00bf8f99b 100644
--- a/lib/mutant/transform.rb
+++ b/lib/mutant/transform.rb
@@ -414,5 +414,11 @@ def call(input)
           .lmap { |exception| error(input: input, message: exception.to_s) }
       end
     end # Exception
+
+    BOOLEAN      = Transform::Boolean.new
+    FLOAT        = Transform::Primitive.new(Float)
+    INTEGER      = Transform::Primitive.new(Integer)
+    STRING       = Transform::Primitive.new(String)
+    STRING_ARRAY = Transform::Array.new(STRING)
   end # Transform
 end # Mutant
diff --git a/spec/support/corpus.rb b/spec/support/corpus.rb
index 216bd5992..ba52d3d66 100644
--- a/spec/support/corpus.rb
+++ b/spec/support/corpus.rb
@@ -274,23 +274,19 @@ def system(arguments)
 
       Transform = Mutant::Transform
 
-      boolean      = Transform::Boolean.new
-      string       = Transform::Primitive.new(String)
-      string_array = Transform::Array.new(string)
-
       integration = Transform::Sequence.new(
         [
           Transform::Hash.new(
             optional: [],
             required: [
-              Transform::Hash::Key.new('exclude',             string_array),
-              Transform::Hash::Key.new('integration',         string),
-              Transform::Hash::Key.new('mutation_coverage',   boolean),
-              Transform::Hash::Key.new('mutation_generation', boolean),
-              Transform::Hash::Key.new('name',                string),
-              Transform::Hash::Key.new('namespace',           string),
-              Transform::Hash::Key.new('repo_ref',            string),
-              Transform::Hash::Key.new('repo_uri',            string)
+              Transform::Hash::Key.new('exclude',             Transform::STRING_ARRAY),
+              Transform::Hash::Key.new('integration',         Transform::STRING),
+              Transform::Hash::Key.new('mutation_coverage',   Transform::BOOLEAN),
+              Transform::Hash::Key.new('mutation_generation', Transform::BOOLEAN),
+              Transform::Hash::Key.new('name',                Transform::STRING),
+              Transform::Hash::Key.new('namespace',           Transform::STRING),
+              Transform::Hash::Key.new('repo_ref',            Transform::STRING),
+              Transform::Hash::Key.new('repo_uri',            Transform::STRING)
             ]
           ),
           Transform::Hash::Symbolize.new,