diff --git a/doc/index.rst b/doc/index.rst
index 0ec4c89538ac2dcd2d176e623ab86b647388e723..02fb16e0ee37d5fe31b20fce8f0e4e33e11c2ef2 100644
--- a/doc/index.rst
+++ b/doc/index.rst
@@ -38,8 +38,8 @@ The Arbor software can be cited by version via Zenodo or via Arbors introductory
 Latest version
     |zlatest|
 
-Version 0.5
-    |z05|
+Version 0.5.2
+    |z052|
 
     .. code-block:: latex
 
@@ -91,6 +91,9 @@ Introductory paper
 .. |zlatest| image:: https://zenodo.org/badge/DOI/10.5281/zenodo.1459678.svg
     :target: https://doi.org/10.5281/zenodo.1459678
 
+.. |z052| image:: https://zenodo.org/badge/DOI/10.5281/zenodo.5031633.svg
+    :target: https://doi.org/10.5281/zenodo.5031633
+
 .. |z05| image:: https://zenodo.org/badge/DOI/10.5281/zenodo.4428108.svg
     :target: https://doi.org/10.5281/zenodo.4428108
 
diff --git a/spack/package.py b/spack/package.py
index 191c5a4d40f22926a24821347e72b4416197de9b..94b9e78cfabcc8f542a8a450c54fe222365463bc 100644
--- a/spack/package.py
+++ b/spack/package.py
@@ -73,7 +73,9 @@ class Arbor(CMakePackage, CudaPackage):
 
         # query spack for the architecture-specific compiler flags set by its wrapper
         args.append('-DARB_ARCH=none')
-        opt_flags = self.spec.target.optimization_flags(self.spec.compiler.name, self.spec.compiler.version)
-        args.append('-DARB_CXX_FLAGS_TARGET='+opt_flags)
+        opt_flags = self.spec.target.optimization_flags(
+            self.spec.compiler.name,
+            self.spec.compiler.version)
+        args.append('-DARB_CXX_FLAGS_TARGET=' + opt_flags)
 
         return args