diff --git a/var/spack/repos/builtin/packages/xrootd/package.py b/var/spack/repos/builtin/packages/xrootd/package.py
index 94ee3eda469..2514997f88a 100644
--- a/var/spack/repos/builtin/packages/xrootd/package.py
+++ b/var/spack/repos/builtin/packages/xrootd/package.py
@@ -39,3 +39,4 @@ class Xrootd(CMakePackage):
     version('4.3.0', '39c2fab9f632f35e12ff607ccaf9e16c')
 
     depends_on('cmake@2.6:', type='build')
+    depends_on('zlib')