diff --git a/check_nut.py b/check_nut.py
index 9da1eb6..00fe2bf 100644
--- a/check_nut.py
+++ b/check_nut.py
@@ -44,6 +44,14 @@ VALUE_COMPARISONS = {
     'input_voltage': 'le',
     'output_voltage': 'le'
 }
+VALUE_UNITS = {
+    'load': '%',
+    'battery_charge': 'V',
+    'battery_runtime': 's',
+    'battery_voltage': 'V',
+    'input_voltage': 'V',
+    'output_voltage': 'V'
+}
 
 
 def parse_ups_status(status: str):
@@ -103,6 +111,8 @@ def main(args):
             if len(lines) and 'data stale' in lines[0].lower():
                 print_icinga2_check_status(f'Failed to get UPS status: data stale', nagios.STATE_CRIT)
                 sys.exit(nagios.STATE_CRIT)
+            else:
+                print_icinga2_check_status(f'Failed to get UPS status: {output}', nagios.STATE_UNKNOWN)
         print_icinga2_check_status(f'Failed to get UPS status: {e}', nagios.STATE_UNKNOWN)
         sys.exit(nagios.STATE_UNKNOWN)
 
@@ -155,7 +165,7 @@ def main(args):
     perf_data = {}
     for k, v in ups_stats.items():
         name = k.replace('.', '_')
-        perf_data[name] = {'value': try_float(v), 'warn': None, 'crit': None, 'min': 0}
+        perf_data[name] = {'value': try_float(v), 'warn': None, 'crit': None, 'min': 0, 'unit': VALUE_UNITS.get(name)}
 
     # Set the perfdata values based on the levels.
     if perf_data.get('battery_charge'):