diff --git a/package/Win32-Inno/FlightGear-1.9.iss b/package/Win32-Inno/FlightGear-1.9.iss
index 34b9df29f..0cdd2ebc8 100755
--- a/package/Win32-Inno/FlightGear-1.9.iss
+++ b/package/Win32-Inno/FlightGear-1.9.iss
@@ -20,18 +20,18 @@
 
 [Setup]
 AppName=FlightGear
-OutputBaseFilename=fgsetup-1.9.0
-AppVerName=FlightGear v1.9.0
+OutputBaseFilename=fgsetup-1.9.1
+AppVerName=FlightGear v1.9.1
 AppPublisher=The FlightGear Organization
 AppPublisherURL=http://www.flightgear.org
 AppSupportURL=http://www.flightgear.org
 AppUpdatesURL=http://www.flightgear.org
 DefaultDirName={pf}\FlightGear
-DefaultGroupName=FlightGear v1.9.0
+DefaultGroupName=FlightGear v1.9.1
 LicenseFile=X:\data\COPYING
 Uninstallable=yes
 SetupIconFile=x:\flightgear.ico
-VersionInfoVersion=1.9.0.0
+VersionInfoVersion=1.9.1.0
 WizardImageFile=X:\setupimg.bmp
 WizardSmallImageFile=X:\setupsmall.bmp
 
@@ -53,7 +53,7 @@ Name: "{group}\FlightGear Launcher"; Filename: "{app}\bin\Win32\fgrun.exe"; Work
 Name: "{group}\FlightGear Manual"; Filename: "{app}\data\Docs\getstart.pdf"
 Name: "{group}\FlightGear Documentation"; Filename: "{app}\data\Docs\index.html"
 Name: "{group}\Flightgear Wiki"; Filename: "http://wiki.flightgear.org"
-Name: "{userdesktop}\FlightGear v1.9.0"; Filename: "{app}\bin\Win32\fgrun.exe"; WorkingDir: "{app}"; Tasks: desktopicon
+Name: "{userdesktop}\FlightGear v1.9.1"; Filename: "{app}\bin\Win32\fgrun.exe"; WorkingDir: "{app}"; Tasks: desktopicon
 
 Name: "{group}\Tools\Install & Uninstall Scenery"; Filename: "{app}\bin\Win32\fgadmin.exe"; WorkingDir: "{app}";
 Name: "{group}\Tools\TerraSync"; Filename: "{app}\bin\Win32\terrasync.exe"; Parameters: "-S -p 5505 -d ""{app}\terrasync"""; WorkingDir: "{app}";
@@ -69,7 +69,7 @@ Name: "{group}\Tools\yasim"; Filename: "cmd"; Parameters: "/k ""{app}\bin\Win32\
 Name: "{group}\Tools\Explore Documentation Folder"; Filename: "{app}\data\Docs"
 
 ; For running flightgear directly
-; Name: "{userdesktop}\FlightGear v1.9.0"; Filename: "{app}\bin\Win32\fgfs.exe"; Parameters: "--fg-root=."; WorkingDir: "{app}"; Tasks: desktopicon
+; Name: "{userdesktop}\FlightGear v1.9.1"; Filename: "{app}\bin\Win32\fgfs.exe"; Parameters: "--fg-root=."; WorkingDir: "{app}"; Tasks: desktopicon
 
 [Run]
 ; Put installation directory into the fgrun.prefs
diff --git a/src/Environment/environment_ctrl.cxx b/src/Environment/environment_ctrl.cxx
index 72f6f0979..cf9c6505f 100644
--- a/src/Environment/environment_ctrl.cxx
+++ b/src/Environment/environment_ctrl.cxx
@@ -438,15 +438,19 @@ FGMetarEnvironmentCtrl::update_env_config ()
         // factor by the maximum wind change.
         double x = fabs(current[0] - metar[0]);
         double y = fabs(current[1] - metar[1]);
-        double dx = x / (x + y);
-        double dy = 1 - dx;
 
-        double maxdx = dx * MaxWindChangeKtsSec;
-        double maxdy = dy * MaxWindChangeKtsSec;
+        // only interpolate if we have a difference
+        if (x + y > 0) {
+            double dx = x / (x + y);
+            double dy = 1 - dx;
 
-        // Interpolate each component separately.
-        current[0] = interpolate_val(current[0], metar[0], maxdx);
-        current[1] = interpolate_val(current[1], metar[1], maxdy);
+            double maxdx = dx * MaxWindChangeKtsSec;
+            double maxdy = dy * MaxWindChangeKtsSec;
+
+            // Interpolate each component separately.
+            current[0] = interpolate_val(current[0], metar[0], maxdx);
+            current[1] = interpolate_val(current[1], metar[1], maxdy);
+        }
 
         // Now convert back to polar coordinates.
         if ((current[0] == 0.0) && (current[1] == 0.0)) {
diff --git a/src/Instrumentation/altimeter.cxx b/src/Instrumentation/altimeter.cxx
index 8e9fbb1c9..0f8d5fc2c 100644
--- a/src/Instrumentation/altimeter.cxx
+++ b/src/Instrumentation/altimeter.cxx
@@ -47,6 +47,7 @@ Altimeter::init ()
 
     SGPropertyNode *node = fgGetNode(branch.c_str(), _num, true );
     raw_PA = 0.0;
+    _kollsman = 0.0;
     _pressure_node     = fgGetNode(_static_pressure.c_str(), true);
     _serviceable_node  = node->getChild("serviceable", 0, true);
     _setting_node      = node->getChild("setting-inhg", 0, true);