diff --git a/Library/Homebrew/test/test_dependency_collector.rb b/Library/Homebrew/test/test_dependency_collector.rb
index 6500afca3a..7067b95e50 100644
--- a/Library/Homebrew/test/test_dependency_collector.rb
+++ b/Library/Homebrew/test/test_dependency_collector.rb
@@ -20,7 +20,7 @@ class DependencyCollectorTests < Test::Unit::TestCase
   def test_dependency_creation
     @d.add 'foo' => :build
     @d.add 'bar' => ['--universal', :optional]
-    assert_not_nil @d.find_dependency('foo')
+    assert_instance_of Dependency, @d.find_dependency('foo')
     assert_equal 2, @d.find_dependency('bar').tags.length
   end
 
@@ -45,7 +45,7 @@ class DependencyCollectorTests < Test::Unit::TestCase
 
   def test_requirement_creation
     @d.add :x11
-    assert_not_nil @d.find_requirement(X11Dependency)
+    assert_instance_of X11Dependency, @d.find_requirement(X11Dependency)
   end
 
   def test_no_duplicate_requirements
diff --git a/Library/Homebrew/test/test_formula.rb b/Library/Homebrew/test/test_formula.rb
index 33b59f93ef..9de2b2eda5 100644
--- a/Library/Homebrew/test/test_formula.rb
+++ b/Library/Homebrew/test/test_formula.rb
@@ -160,7 +160,6 @@ class FormulaTests < Test::Unit::TestCase
   def test_head_only_specs
     f = HeadOnlySpecTestBall.new
 
-    assert_not_nil f.head
     assert_nil f.stable
     assert_nil f.bottle
     assert_nil f.devel
@@ -177,7 +176,6 @@ class FormulaTests < Test::Unit::TestCase
   def test_incomplete_stable_specs
     f = IncompleteStableSpecTestBall.new
 
-    assert_not_nil f.head
     assert_nil f.stable
     assert_nil f.bottle
     assert_nil f.devel
@@ -194,7 +192,6 @@ class FormulaTests < Test::Unit::TestCase
   def test_head_only_with_version_specs
     f = IncompleteStableSpecTestBall.new
 
-    assert_not_nil f.head
     assert_nil f.stable
     assert_nil f.bottle
     assert_nil f.devel
@@ -211,9 +208,9 @@ class FormulaTests < Test::Unit::TestCase
   def test_explicit_strategy_specs
     f = ExplicitStrategySpecTestBall.new
 
-    assert_not_nil f.stable
-    assert_not_nil f.devel
-    assert_not_nil f.head
+    assert_instance_of SoftwareSpec, f.stable
+    assert_instance_of SoftwareSpec, f.devel
+    assert_instance_of HeadSoftwareSpec, f.head
 
     assert_equal f.stable, f.active_spec