diff --git a/scripts/ccpp_prebuild.py b/scripts/ccpp_prebuild.py
index 68353ed3..29e6e069 100755
--- a/scripts/ccpp_prebuild.py
+++ b/scripts/ccpp_prebuild.py
@@ -378,7 +378,7 @@ def check_optional_arguments(metadata, arguments, optional_arguments):
             # *DH 2020-05-26
             for subroutine_name in optional_arguments[module_name].keys():
                 # If optional arguments are listed individually, check each of them
-                if type(optional_arguments[module_name][subroutine_name]) is list:
+                if isinstance(optional_arguments[module_name][subroutine_name], list):
                     for var_name in optional_arguments[module_name][subroutine_name]:
                         if not var_name in arguments[module_name][scheme_name][subroutine_name]:
                             raise Exception("Explicitly requested optional argument '{}' not known to {}/{}".format(
diff --git a/scripts/conversion_tools/unit_conversion.py b/scripts/conversion_tools/unit_conversion.py
index b61d670a..b8d50707 100755
--- a/scripts/conversion_tools/unit_conversion.py
+++ b/scripts/conversion_tools/unit_conversion.py
@@ -113,7 +113,35 @@ def kg_kg_minus_1__to__g_kg_minus_1():
 
 def g_kg_minus_1__to__kg_kg_minus_1():
     """Convert gram per kilogram to kilogram per kilogram"""
-    return '{var}/1.0E+3{kind}'
+    return '1.0E-3{kind}*{var}'
+
+##################
+# Plane angle    #
+##################
+
+def radian__to__degree():
+    """Convert radian to degree"""
+    return '57.295779513{kind}*{var}'
+
+def degree__to__radian():
+    """Convert degree to radian"""
+    return '{var}/57.295779513{kind}'
+
+def radian__to__degree_north():
+    """Convert radian to degree north"""
+    return radian__to__degree()
+
+def degree_north__to__radian():
+    """Convert degree north to radian"""
+    return degree__to__radian()
+
+def radian__to__degree_east():
+    """Convert radian to degree east"""
+    return radian__to__degree()
+
+def degree_east__to__radian():
+    """Convert degree east to radian"""
+    return degree__to__radian()
 
 ##################
 # Composed units #
diff --git a/scripts/metadata2html.py b/scripts/metadata2html.py
index 148a081e..2e27ea3a 100755
--- a/scripts/metadata2html.py
+++ b/scripts/metadata2html.py
@@ -74,7 +74,7 @@ def import_config(configfile, logger):
 def get_metadata_files_from_config(config, logger):
     """Create a list of metadata filenames for a CCPP prebuild configuration"""
     filenames = []
-    for sourcefile in config['variable_definition_files'] + config['scheme_files'].keys():
+    for sourcefile in config['variable_definition_files'] + config['scheme_files']:
         metafile = os.path.splitext(sourcefile)[0]+'.meta'
         if os.path.isfile(metafile):
             filenames.append(metafile)
diff --git a/scripts/mkcap.py b/scripts/mkcap.py
index 9170424c..06e59d37 100755
--- a/scripts/mkcap.py
+++ b/scripts/mkcap.py
@@ -91,7 +91,7 @@ def dimensions(self):
 
     @dimensions.setter
     def dimensions(self, value):
-        if not type(value) is list:
+        if not isinstance(value, list):
             raise TypeError('Invalid type for variable property dimensions, must be a list')
         self._dimensions = value
 
@@ -170,7 +170,7 @@ def actions(self):
 
     @actions.setter
     def actions(self, values):
-        if type(values)==dict:
+        if isinstance(values, dict):
             for key in values.keys():
                 if key in ['in', 'out'] and isstring(values[key]):
                     self._actions[key] = values[key]