diff --git a/lib/spack/spack/test/spec_semantics.py b/lib/spack/spack/test/spec_semantics.py
index 3b0c4ce391f..c3e18af44df 100644
--- a/lib/spack/spack/test/spec_semantics.py
+++ b/lib/spack/spack/test/spec_semantics.py
@@ -695,6 +695,7 @@ def test_constrain_dependency_changed(self):
         check_constrain_changed('libelf^foo%gcc', 'libelf^foo%gcc@4.5')
         check_constrain_changed('libelf^foo', 'libelf^foo+debug')
         check_constrain_changed('libelf^foo', 'libelf^foo~debug')
+        check_constrain_changed('libelf', '^foo')
 
         platform = spack.architecture.platform()
         default_target = platform.target('default_target').name