diff --git a/js/drivers/sref/osie.js b/js/drivers/sref/osie.js
index 137e4aaf..89febcf5 100644
--- a/js/drivers/sref/osie.js
+++ b/js/drivers/sref/osie.js
@@ -23,7 +23,7 @@ if (typeof indiciaData.srefHandlers==="undefined") {
 
 indiciaData.srefHandlers['osie'] = {
 
-  srid: 29901,
+  srid: 29903,
 
   returns: ['wkt', 'precisions', 'gridNotation'],
 
diff --git a/js/jquery.indiciaMapPanel.js b/js/jquery.indiciaMapPanel.js
index c384f4a1..e034eced 100644
--- a/js/jquery.indiciaMapPanel.js
+++ b/js/jquery.indiciaMapPanel.js
@@ -2250,7 +2250,7 @@ var destroyAllFeatures;
           && wmPoint.x >= -1196000 && wmPoint.x <= -599200 && wmPoint.y >= 6687800 && wmPoint.y <= 7442470) {
         // Got a rough match, now transform to the correct system so we can do exact match. Note that we are not testing against
         // a pure rectangle now.
-        proj = new OpenLayers.Projection('EPSG:29901');
+        proj = new OpenLayers.Projection('EPSG:29903');
         testpoint = wmPoint.clone().transform(wmProj, proj);
         if (testpoint.x >= 10000 && testpoint.x <= 367300 && testpoint.y >= 10000 && testpoint.y <= 468100
             && (testpoint.x < 332000 || testpoint.y < 445900)) {
@@ -2319,7 +2319,7 @@ var destroyAllFeatures;
         if (wmPoint.x >= -1196000 && wmPoint.x <= -599200 && wmPoint.y >= 6687800 && wmPoint.y <= 7442470) {
           // Got a rough match, now transform to the correct system so we can do exact match. Note that we are not testing against
           // a pure rectangle now.
-          proj = new OpenLayers.Projection('EPSG:29901');
+          proj = new OpenLayers.Projection('EPSG:29903');
           testpoint = wmPoint.clone().transform(wmProj, proj);
           if (testpoint.x >= 10000 && testpoint.x <= 367300 && testpoint.y >= 10000 && testpoint.y <= 468100
               && (testpoint.x < 332000 || testpoint.y < 445900)) {
@@ -3860,7 +3860,7 @@ jQuery.fn.indiciaMapPanel.defaults = {
       intervals: [100000, 10000, 1000, 100]
     },
     'OSIE': {
-      projection: 29901,
+      projection: 29903,
       bounds: [0, 0, 400000, 500000],
       intervals: [100000, 10000, 1000, 100]
     },
diff --git a/js/proj4defs.js b/js/proj4defs.js
index 67faf8d1..bbf3bd72 100644
--- a/js/proj4defs.js
+++ b/js/proj4defs.js
@@ -6,6 +6,7 @@ Proj4js.defs["EPSG:3857"] = Proj4js.defs["GOOGLE"];
 Proj4js.defs["EPSG:4314"] = "+proj=longlat +ellps=bessel +datum=potsdam +no_defs";
 Proj4js.defs["EPSG:27700"] = "+proj=tmerc +lat_0=49 +lon_0=-2 +k=0.9996012717 +x_0=400000 +y_0=-100000 +ellps=airy +datum=OSGB36 +units=m +no_defs";
 Proj4js.defs["EPSG:29901"] = "+proj=tmerc +lat_0=53.5 +lon_0=-8 +k=1 +x_0=200000 +y_0=250000 +ellps=airy +towgs84=482.5,-130.6,564.6,-1.042,-0.214,-0.631,8.15 +units=m +no_defs";
+Proj4js.defs["EPSG:29903"] = "+proj=tmerc +lat_0=53.5 +lon_0=-8 +k=1.000035 +x_0=200000 +y_0=250000 +a=6377340.189 +rf=299.3249646 +towgs84=482.5,-130.6,564.6,-1.042,-0.214,-0.631,8.15 +units=m +no_defs +type=crs";
 Proj4js.defs["EPSG:31462"] = "+proj=tmerc +lat_0=0 +lon_0=6 +k=1 +x_0=2500000 +y_0=0 +ellps=bessel +datum=potsdam +units=m +no_defs";
 Proj4js.defs["EPSG:31463"] = "+proj=tmerc +lat_0=0 +lon_0=9 +k=1 +x_0=3500000 +y_0=0 +ellps=bessel +datum=potsdam +units=m +no_defs";
 Proj4js.defs["EPSG:31464"] = "+proj=tmerc +lat_0=0 +lon_0=12 +k=1 +x_0=4500000 +y_0=0 +ellps=bessel +datum=potsdam +units=m +no_defs";