diff --git a/docs/changes.txt b/docs/changes.txt
index c9304a16d0..fa28d309df 100644
--- a/docs/changes.txt
+++ b/docs/changes.txt
@@ -619,6 +619,7 @@ wxGTK:
 
 - Fix infinite sizing loop with GTK3 when using wxScrolled with a non-default
   target window.
+- Fix wxBitmap ctor from XBM for non-square bitmaps.
 - Fix crashes in wxGTK3 when running with non-X11 backend (Marco Trevisan).
 - Fix coordinates of wxSetCursorEvent propagated to parent windows.
 - Fix GTK+ warnings when refreshing wxListCtrl items (Scott Talbert).
diff --git a/src/gtk/bitmap.cpp b/src/gtk/bitmap.cpp
index f81e7104a8..d3abc4c89b 100644
--- a/src/gtk/bitmap.cpp
+++ b/src/gtk/bitmap.cpp
@@ -428,17 +428,18 @@ wxBitmap::wxBitmap(const char bits[], int width, int height, int depth)
         const char* src = bits;
         guchar* dst = gdk_pixbuf_get_pixels(pixbuf);
         const int stride_src = (width + 7) / 8;
-        const int rowinc_dst = gdk_pixbuf_get_rowstride(pixbuf) - 3 * width;
-        for (int j = 0; j < width; j++, src += stride_src, dst += rowinc_dst)
+        const int stride_dst = gdk_pixbuf_get_rowstride(pixbuf);
+        for (int j = 0; j < height; j++, src += stride_src, dst += stride_dst)
         {
-            for (int i = 0; i < height; i++)
+            guchar* d = dst;
+            for (int i = 0; i < width; i++)
             {
                 guchar c = 0xff;
                 if (src[i >> 3] & (1 << (i & 7)))
                     c = 0;
-                *dst++ = c;
-                *dst++ = c;
-                *dst++ = c;
+                *d++ = c;
+                *d++ = c;
+                *d++ = c;
             }
         }
 #else