diff --git a/src/lib/code39barcode.cpp b/src/lib/code39barcode.cpp
--- a/src/lib/code39barcode.cpp
+++ b/src/lib/code39barcode.cpp
@@ -142,6 +142,7 @@
   // then maximize narrow bar width
   int smallWidth = (w - largeWidth*wide) / narrow;
   // if the requested size was too small return a null image
+  setMinimumSize(QSize(2* wide + narrow, 10));
   if(largeWidth<2) {
       return QImage();
   }
diff --git a/src/lib/code93barcode.cpp b/src/lib/code93barcode.cpp
--- a/src/lib/code93barcode.cpp
+++ b/src/lib/code93barcode.cpp
@@ -291,6 +291,7 @@
 
   // try to fill the requested size
   const int barWidth = int(size.width() / barcode.size());
+  setMinimumSize(QSize(barcode.size(), 10));
   if(barWidth < 1 ) { // can't go below 1 pixel
       return QImage();
   }