diff --git a/Library/Homebrew/formula.rb b/Library/Homebrew/formula.rb
index b3927d260b..600f9c2e97 100644
--- a/Library/Homebrew/formula.rb
+++ b/Library/Homebrew/formula.rb
@@ -1505,7 +1505,7 @@ class Formula
   # Returns a list of Dependency objects that are required at runtime.
   # @private
   def runtime_dependencies
-    recursive_dependencies.reject(&:build?)
+    recursive_dependencies { |_, dep| Dependency.prune if dep.build? }
   end
 
   # Returns a list of formulae depended on by this formula that aren't
diff --git a/Library/Homebrew/test/formula_test.rb b/Library/Homebrew/test/formula_test.rb
index a6db1b57f2..28d376b7c2 100644
--- a/Library/Homebrew/test/formula_test.rb
+++ b/Library/Homebrew/test/formula_test.rb
@@ -651,12 +651,19 @@ class FormulaTests < Homebrew::TestCase
 
     f4 = formula("f4") do
       url "f4-1.0"
-      depends_on "f3"
+      depends_on "f1"
+    end
+    stub_formula_loader f4
+
+    f5 = formula("f5") do
+      url "f5-1.0"
+      depends_on "f3" => :build
+      depends_on "f4"
     end
 
-    assert_equal %w[f3], f4.deps.map(&:name)
-    assert_equal %w[f1 f2 f3], f4.recursive_dependencies.map(&:name)
-    assert_equal %w[f2 f3], f4.runtime_dependencies.map(&:name)
+    assert_equal %w[f3 f4], f5.deps.map(&:name)
+    assert_equal %w[f1 f2 f3 f4], f5.recursive_dependencies.map(&:name)
+    assert_equal %w[f1 f4], f5.runtime_dependencies.map(&:name)
   end
 
   def test_to_hash