diff --git a/data/org.gnome.shell.extensions.openweather.gschema.xml.in b/data/org.gnome.shell.extensions.openweather.gschema.xml.in
index be51e90..c740f27 100644
--- a/data/org.gnome.shell.extensions.openweather.gschema.xml.in
+++ b/data/org.gnome.shell.extensions.openweather.gschema.xml.in
@@ -23,6 +23,7 @@
     <value nick="at" value="6" />
     <value nick="Torr" value="7" />
     <value nick="psi" value="8" />
+    <value nick="mmHg" value="9" />
   </enum>
   <enum id="org.gnome.shell.extensions.openweather.wind-speed-unit">
     <value nick="kph" value="0" />
diff --git a/data/weather-settings.ui b/data/weather-settings.ui
index b326e75..ed57bdd 100644
--- a/data/weather-settings.ui
+++ b/data/weather-settings.ui
@@ -639,6 +639,7 @@
                       <item>at</item>
                       <item>Torr</item>
                       <item>psi</item>
+                      <item>mmHg</item>
                     </items>
                   </object>
                   <packing>
diff --git a/src/extension.js b/src/extension.js
index 5616c0d..10dc631 100644
--- a/src/extension.js
+++ b/src/extension.js
@@ -109,15 +109,16 @@ const WeatherWindSpeedUnits = {
 };
 
 const WeatherPressureUnits = {
-    hPa: 0,
-    inHg: 1,
-    bar: 2,
-    Pa: 3,
-    kPa: 4,
-    atm: 5,
-    at: 6,
-    Torr: 7,
-    psi: 8
+    HPA: 0,
+    INHG: 1,
+    BAR: 2,
+    PA: 3,
+    KPA: 4,
+    ATM: 5,
+    AT: 6,
+    TORR: 7,
+    PSI: 8,
+    MMHG: 9
 };
 
 const WeatherPosition = {
@@ -980,50 +981,55 @@ const OpenweatherMenuButton = new Lang.Class({
     formatPressure: function(pressure) {
         let pressure_unit = 'hPa';
         switch (this._pressure_units) {
-            case WeatherPressureUnits.inHg:
+            case WeatherPressureUnits.INHG:
                 pressure = this.toInHg(pressure);
                 pressure_unit = "inHg";
                 break;
 
-            case WeatherPressureUnits.hPa:
+            case WeatherPressureUnits.HPA:
                 pressure = pressure.toFixed(this._decimal_places);
                 pressure_unit = "hPa";
                 break;
 
-            case WeatherPressureUnits.bar:
+            case WeatherPressureUnits.BAR:
                 pressure = (pressure / 1000).toFixed(this._decimal_places);
                 pressure_unit = "bar";
                 break;
 
-            case WeatherPressureUnits.Pa:
+            case WeatherPressureUnits.PA:
                 pressure = (pressure * 100).toFixed(this._decimal_places);
                 pressure_unit = "Pa";
                 break;
 
-            case WeatherPressureUnits.kPa:
+            case WeatherPressureUnits.KPA:
                 pressure = (pressure / 10).toFixed(this._decimal_places);
                 pressure_unit = "kPa";
                 break;
 
-            case WeatherPressureUnits.atm:
+            case WeatherPressureUnits.ATM:
                 pressure = (pressure * 0.000986923267).toFixed(this._decimal_places);
                 pressure_unit = "atm";
                 break;
 
-            case WeatherPressureUnits.at:
+            case WeatherPressureUnits.AT:
                 pressure = (pressure * 0.00101971621298).toFixed(this._decimal_places);
                 pressure_unit = "at";
                 break;
 
-            case WeatherPressureUnits.Torr:
+            case WeatherPressureUnits.TORR:
                 pressure = (pressure * 0.750061683).toFixed(this._decimal_places);
                 pressure_unit = "Torr";
                 break;
 
-            case WeatherPressureUnits.psi:
+            case WeatherPressureUnits.PSI:
                 pressure = (pressure * 0.0145037738).toFixed(this._decimal_places);
                 pressure_unit = "psi";
                 break;
+
+            case WeatherPressureUnits.MMHG:
+                pressure = (pressure * 0.750061683).toFixed(this._decimal_places);
+                pressure_unit = "mmHg";
+                break;
         }
         return parseFloat(pressure).toLocaleString() + ' ' + pressure_unit;
     },