diff --git a/MapProjections/Shared/Ed50UtmProjection.cs b/MapProjections/Shared/Ed50UtmProjection.cs
index 3f0bd0d2..332a5094 100644
--- a/MapProjections/Shared/Ed50UtmProjection.cs
+++ b/MapProjections/Shared/Ed50UtmProjection.cs
@@ -46,7 +46,7 @@ namespace MapControl.Projections
                 + "UNIT[\"metre\",1,AUTHORITY[\"EPSG\",\"9001\"]],"
                 + "AXIS[\"Easting\",EAST],"
                 + "AXIS[\"Northing\",NORTH],"
-                + $"AUTHORITY[\"EPSG\",\"230{zone}\"]]";
+                + $"AUTHORITY[\"EPSG\",\"230{zone:00}\"]]";
         }
     }
 }
diff --git a/MapProjections/Shared/Etrs89UtmProjection.cs b/MapProjections/Shared/Etrs89UtmProjection.cs
index 20be7779..22dbb0dd 100644
--- a/MapProjections/Shared/Etrs89UtmProjection.cs
+++ b/MapProjections/Shared/Etrs89UtmProjection.cs
@@ -46,7 +46,7 @@ namespace MapControl.Projections
                 + "UNIT[\"metre\",1,AUTHORITY[\"EPSG\",\"9001\"]],"
                 + "AXIS[\"Easting\",EAST],"
                 + "AXIS[\"Northing\",NORTH],"
-                + $"AUTHORITY[\"EPSG\",\"258{zone}\"]]";
+                + $"AUTHORITY[\"EPSG\",\"258{zone:00}\"]]";
         }
     }
 }
diff --git a/MapProjections/Shared/Nad27UtmProjection.cs b/MapProjections/Shared/Nad27UtmProjection.cs
index 9de09ba8..ecd06ead 100644
--- a/MapProjections/Shared/Nad27UtmProjection.cs
+++ b/MapProjections/Shared/Nad27UtmProjection.cs
@@ -44,7 +44,7 @@ namespace MapControl.Projections
                 + "UNIT[\"metre\",1,AUTHORITY[\"EPSG\",\"9001\"]],"
                 + "AXIS[\"Easting\",EAST],"
                 + "AXIS[\"Northing\",NORTH],"
-                + $"AUTHORITY[\"EPSG\",\"267{zone}\"]]";
+                + $"AUTHORITY[\"EPSG\",\"267{zone:00}\"]]";
         }
     }
 }
diff --git a/MapProjections/Shared/Nad83UtmProjection.cs b/MapProjections/Shared/Nad83UtmProjection.cs
index 5267f124..dd214495 100644
--- a/MapProjections/Shared/Nad83UtmProjection.cs
+++ b/MapProjections/Shared/Nad83UtmProjection.cs
@@ -44,7 +44,7 @@ namespace MapControl.Projections
                 + "UNIT[\"metre\",1,AUTHORITY[\"EPSG\",\"9001\"]],"
                 + "AXIS[\"Easting\",EAST],"
                 + "AXIS[\"Northing\",NORTH],"
-                + $"AUTHORITY[\"EPSG\",\"269{zone}\"]]";
+                + $"AUTHORITY[\"EPSG\",\"269{zone:00}\"]]";
         }
     }
 }