diff --git a/var/spack/repos/builtin/packages/plumed/package.py b/var/spack/repos/builtin/packages/plumed/package.py
index c261e90fd8a95db27e9c6d55897ee560521b6a14..3d9e8222ba1fa8adee98e9b89e64986edf52e902 100644
--- a/var/spack/repos/builtin/packages/plumed/package.py
+++ b/var/spack/repos/builtin/packages/plumed/package.py
@@ -121,7 +121,7 @@ def install(self, spec, prefix):
             if spec.satisfies('^intelmpi'):
                 configure_opts.extend([
                     'STATIC_LIBS=-mt_mpi'
-                ]) 
+                ])
 
         # Additional arguments
         configure_opts.extend([
@@ -130,7 +130,7 @@ def install(self, spec, prefix):
         ])
 
         # Construct list of optional modules
-        module_opts=[]
+        module_opts = []
         module_opts.extend([
             '+crystallization' if (
                 '+crystallization' in spec) else '-crystallization',