diff --git a/config/reek.yml b/config/reek.yml
index 59810dc7..ef930a64 100644
--- a/config/reek.yml
+++ b/config/reek.yml
@@ -36,7 +36,7 @@ ControlParameter:
   - Axiom::Function::Connective::Conjunction#self.call
   - Axiom::Function::Connective::Disjunction#self.call
   - Axiom::Function::Predicate::Enumerable#self.compare_method
-  - Axiom::Relation::Operation::Limit::Methods#assert_no_more_than_one_tuple
+  - Axiom::Relation#assert_no_more_than_one_tuple
 DataClump:
   enabled: true
   exclude:
diff --git a/lib/axiom/relation.rb b/lib/axiom/relation.rb
index 4e616a66..69a3e4cb 100644
--- a/lib/axiom/relation.rb
+++ b/lib/axiom/relation.rb
@@ -7,6 +7,12 @@ class Relation
     include Enumerable, Visitable, Adamantium::Flat
     include Equalizer.new(:header, :to_set)
 
+    # Default block used in #one
+    DEFAULT_ONE_BLOCK = -> {}
+
+    # Maximum number of tuples to take in #one
+    ONE_LIMIT = 2
+
     # The relation header
     #
     # @return [Header]
@@ -145,6 +151,32 @@ def replace(other)
       delete(difference(other)).insert(other.difference(self))
     end
 
+    # Return a tuple if the relation contains exactly one tuple
+    #
+    # @example without a block
+    #   tuple = relation.one
+    #
+    # @example with a block
+    #   tuple = relation.one { ... }
+    #
+    # @yieldreturn [Object]
+    #
+    # @return [Tuple]
+    #
+    # @raise [NoTuplesError]
+    #   raised if no tuples are returned
+    # @raise [ManyTuplesError]
+    #   raised if more than one tuple is returned
+    #
+    # @api public
+    def one(&block)
+      block ||= DEFAULT_ONE_BLOCK
+      tuples = sort.take(ONE_LIMIT).to_a
+      assert_no_more_than_one_tuple(tuples.size)
+      tuples.first or block.yield or
+        fail NoTuplesError, 'one tuple expected, but was an empty set'
+    end
+
     # Return a relation with each tuple materialized
     #
     # @example
@@ -245,5 +277,21 @@ def self.coerce(header, object)
       end
     end
 
+    # Assert no more than one tuple is returned
+    #
+    # @return [undefined]
+    #
+    # @raise [ManyTuplesError]
+    #   raised if more than one tuple is returned
+    #
+    # @api private
+    def assert_no_more_than_one_tuple(size)
+      return if size <= 1
+      fail(
+        ManyTuplesError,
+        "one tuple expected, but set contained #{count} tuples"
+      )
+    end
+
   end # class Relation
 end # module Axiom
diff --git a/lib/axiom/relation/operation/limit.rb b/lib/axiom/relation/operation/limit.rb
index 6ac7eb8f..40226e32 100644
--- a/lib/axiom/relation/operation/limit.rb
+++ b/lib/axiom/relation/operation/limit.rb
@@ -150,12 +150,6 @@ def delete(*)
 
         module Methods
 
-          # Default block used in #one
-          DEFAULT_ONE_BLOCK = -> {}
-
-          # Maximum number of tuples to take in #one
-          ONE_LIMIT = 2
-
           # Return a relation with n tuples
           #
           # @example
@@ -207,50 +201,6 @@ def last(limit = 1)
             reverse.take(limit).reverse
           end
 
-          # Return a tuple if the relation contains exactly one tuple
-          #
-          # @example without a block
-          #   tuple = relation.one
-          #
-          # @example with a block
-          #   tuple = relation.one { ... }
-          #
-          # @yieldreturn [Object]
-          #
-          # @return [Tuple]
-          #
-          # @raise [NoTuplesError]
-          #   raised if no tuples are returned
-          # @raise [ManyTuplesError]
-          #   raised if more than one tuple is returned
-          #
-          # @api public
-          def one(&block)
-            block ||= DEFAULT_ONE_BLOCK
-            tuples = take(ONE_LIMIT).to_a
-            assert_no_more_than_one_tuple(tuples.size)
-            tuples.first or block.yield or
-              fail NoTuplesError, 'one tuple expected, but was an empty set'
-          end
-
-        private
-
-          # Assert no more than one tuple is returned
-          #
-          # @return [undefined]
-          #
-          # @raise [ManyTuplesError]
-          #   raised if more than one tuple is returned
-          #
-          # @api private
-          def assert_no_more_than_one_tuple(size)
-            return if size <= 1
-            fail(
-              ManyTuplesError,
-              "one tuple expected, but set contained #{count} tuples"
-            )
-          end
-
         end # module Methods
 
         Relation.class_eval { include Methods }
diff --git a/spec/unit/axiom/relation/operation/limit/methods/one_spec.rb b/spec/unit/axiom/relation/one_spec.rb
similarity index 91%
rename from spec/unit/axiom/relation/operation/limit/methods/one_spec.rb
rename to spec/unit/axiom/relation/one_spec.rb
index 18573001..7308771b 100644
--- a/spec/unit/axiom/relation/operation/limit/methods/one_spec.rb
+++ b/spec/unit/axiom/relation/one_spec.rb
@@ -2,10 +2,10 @@
 
 require 'spec_helper'
 
-describe Relation::Operation::Limit::Methods, '#one' do
+describe Relation, '#one' do
   subject { object.one }
 
-  let(:object) { Relation.new(header, body).sort           }
+  let(:object) { Relation.new(header, body)                }
   let(:header) { Relation::Header.coerce([[:id, Integer]]) }
 
   context 'with a relation having no tuples without a block' do