diff --git a/lib/spack/spack/modules.py b/lib/spack/spack/modules.py
index 6aefbf548e1..56a61adefb9 100644
--- a/lib/spack/spack/modules.py
+++ b/lib/spack/spack/modules.py
@@ -117,8 +117,12 @@ def add_path(path_name, directory):
                     ('PATH', self.spec.prefix.bin),
                     ('MANPATH', self.spec.prefix.man),
                     ('MANPATH', self.spec.prefix.share_man),
+                    ('LIBRARY_PATH', self.spec.prefix.lib),
+                    ('LIBRARY_PATH', self.spec.prefix.lib64),
                     ('LD_LIBRARY_PATH', self.spec.prefix.lib),
-                    ('LD_LIBRARY_PATH', self.spec.prefix.lib64)]:
+                    ('LD_LIBRARY_PATH', self.spec.prefix.lib64),
+                    ('PKG_CONFIG_PATH', join_path(self.spec.prefix.lib, 'pkgconfig')),
+                    ('PKG_CONFIG_PATH', join_path(self.spec.prefix.lib64, 'pkgconfig'))]:
 
                 if os.path.isdir(directory):
                     add_path(var, directory)