diff --git a/var/spack/repos/builtin/packages/glib/package.py b/var/spack/repos/builtin/packages/glib/package.py
index 67ead5f9416b8ece41d191c6cc799232f5f8fcda..a3fc3f79ebe9d6ea095336b366fdb716c050985b 100644
--- a/var/spack/repos/builtin/packages/glib/package.py
+++ b/var/spack/repos/builtin/packages/glib/package.py
@@ -1,4 +1,5 @@
 from spack import *
+import sys
 
 class Glib(Package):
     """The GLib package contains a low-level libraries useful for
@@ -12,6 +13,8 @@ class Glib(Package):
 
     depends_on("libffi")
     depends_on("zlib")
+    depends_on("pkg-config")
+    depends_on('gettext', sys.platform=='darwin')
 
     def install(self, spec, prefix):
         configure("--prefix=%s" % prefix)
diff --git a/var/spack/repos/builtin/packages/libxcb/package.py b/var/spack/repos/builtin/packages/libxcb/package.py
index d7d94c4546e33a3dd6f017b2c45b1ae8c6f8822f..b2543be5da7dca8e963aa90c504213f4cee61ad7 100644
--- a/var/spack/repos/builtin/packages/libxcb/package.py
+++ b/var/spack/repos/builtin/packages/libxcb/package.py
@@ -13,6 +13,7 @@ class Libxcb(Package):
     version('1.11.1', '118623c15a96b08622603a71d8789bf3')
     depends_on("python")
     depends_on("xcb-proto")
+    depends_on("pkg-config")
 
     # depends_on('pthread')    # Ubuntu: apt-get install libpthread-stubs0-dev
     # depends_on('xau')        # Ubuntu: apt-get install libxau-dev