diff --git a/Elwig/Helpers/Printing/Win32Printer.cs b/Elwig/Helpers/Printing/Win32Printer.cs
index 4bf2f7d..3e90a19 100644
--- a/Elwig/Helpers/Printing/Win32Printer.cs
+++ b/Elwig/Helpers/Printing/Win32Printer.cs
@@ -163,15 +163,17 @@ namespace Elwig.Helpers.Printing {
 
             public bool TrySetDuplex(Duplexing duplex) {
                 var devMode = Marshal.PtrToStructure<DEVMODE>(_devMode);
+                switch (duplex) {
+                    case Duplexing.OneSided: devMode.dmDuplex = DMDUP_SIMPLEX; break;
+                    case Duplexing.TwoSidedShortEdge: devMode.dmDuplex = DMDUP_HORIZONTAL; break;
+                    case Duplexing.TwoSidedLongEdge: devMode.dmDuplex = DMDUP_VERTICAL; break;
+                }
                 if ((devMode.dmFields & DM_DUPLEX) != 0) {
-                    switch (duplex) {
-                        case Duplexing.OneSided: devMode.dmDuplex = DMDUP_SIMPLEX; break;
-                        case Duplexing.TwoSidedShortEdge: devMode.dmDuplex = DMDUP_HORIZONTAL; break;
-                        case Duplexing.TwoSidedLongEdge: devMode.dmDuplex = DMDUP_VERTICAL; break;
-                    }
                     Marshal.StructureToPtr(devMode, _devMode, false);
                     return true;
                 } else {
+                    devMode.dmFields |= DM_DUPLEX;
+                    Marshal.StructureToPtr(devMode, _devMode, false);
                     return false;
                 }
             }