diff --git a/app/helpers/body_trackers_helper.rb b/app/helpers/body_trackers_helper.rb
index c568e32..16964c3 100644
--- a/app/helpers/body_trackers_helper.rb
+++ b/app/helpers/body_trackers_helper.rb
@@ -61,7 +61,7 @@ module BodyTrackersHelper
     single_columns = []
     spec[1..-1].each_with_index do |row, i|
       row.each do |q, span|
-        # Current span nil and previous span == 1
+        # Current span is nil and previous span == 1
         if span.nil? && (spec[i][q] == 1)
           spec[i][q] = -(spec.length - i)
           single_columns << q
diff --git a/app/models/quantity.rb b/app/models/quantity.rb
index a825e0e..36c3ce1 100644
--- a/app/models/quantity.rb
+++ b/app/models/quantity.rb
@@ -13,11 +13,20 @@ class Quantity < ActiveRecord::Base
   has_many :exposures, dependent: :destroy
 
   has_one :formula, inverse_of: :quantity, dependent: :destroy, validate: true
-  accepts_nested_attributes_for :formula, allow_destroy: true, reject_if: proc { |attrs|
-    attrs['code'].blank?
-  }
+  accepts_nested_attributes_for :formula, allow_destroy: true,
+    reject_if: proc { |attrs| attrs['code'].blank? }
 
-  validates :name, presence: true, uniqueness: {scope: :project_id}
+  validates :name, presence: true
+  # Quantity :name uniqueness relaxed to formulas unambiguity
+  validate if: -> { name_changed? } do
+    formulas = project.formulas.where('formulas.code LIKE ?', "%#{name}%").includes(:quantity)
+    # FIXME: should actually parse formulas in formulas and check for exact name match;
+    # current code is just quick'n'dirty partial solution
+    if formulas.exists?
+      quantity_names = formulas.map { |f| "'#{f.quantity.name}'" }.join(',')
+      errors.add(:name, :name_ambiguous, names: quantity_names)
+    end
+  end
   validates :domain, inclusion: {in: domains.keys}
   validate if: -> { parent.present? } do
     errors.add(:parent, :parent_domain_mismatch) unless domain == parent.domain
diff --git a/config/locales/en.yml b/config/locales/en.yml
index fa29439..a5af9ff 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -44,6 +44,8 @@ en:
           attributes:
             parent:
               parent_domain_mismatch: 'parent quantity has to be in the same domain'
+            name:
+              name_ambiguous: 'name creates ambiguity in quantity formulas for: %{names}'
         formula:
           attributes:
             code:
diff --git a/lib/body_tracking/project_patch.rb b/lib/body_tracking/project_patch.rb
index 44899f4..8bc992b 100644
--- a/lib/body_tracking/project_patch.rb
+++ b/lib/body_tracking/project_patch.rb
@@ -2,6 +2,7 @@ module BodyTracking::ProjectPatch
   Project.class_eval do
     has_many :sources, dependent: :destroy
     has_many :quantities, -> { order "lft" }, inverse_of: :project, dependent: :destroy
+    has_many :formulas, through: :quantities
     has_many :units, dependent: :destroy
 
     has_many :foods, -> { order "foods.name" }, dependent: :destroy,