diff --git a/plakativ.py b/plakativ.py
index d7d9bbf..7a85e56 100644
--- a/plakativ.py
+++ b/plakativ.py
@@ -49,19 +49,18 @@ class Plakativ:
         assert len(self.doc) == 1
         self.dlist = self.doc[0].getDisplayList()
 
-        self.pagesize = PAGE_SIZES["A4 (21.0 cm × 29.7 cm)"]
         self.border_left = 20
         self.border_right = 20
         self.border_top = 20
         self.border_bottom = 20
         self.config = {
-            "pagesize": (
+            "input_pagesize": (
                 pt_to_mm(self.dlist.rect.width),
                 pt_to_mm(self.dlist.rect.height),
             ),
             "postersize": PAGE_SIZES["A1 (59.4 cm × 84.1 cm)"],
         }
-        self.layout = {"pagesize": PAGE_SIZES["A4 (21.0 cm × 29.7 cm)"]}
+        self.layout = {"output_pagesize": PAGE_SIZES["A4 (21.0 cm × 29.7 cm)"]}
 
     def compute_layout(self, mode, size=None, mult=None, npages=None):
         if self.doc is None:
@@ -80,10 +79,10 @@ class Plakativ:
         else:
             raise Exception("unsupported mode: %s" % mode)
 
-        printable_width = self.layout["pagesize"][0] - (
+        printable_width = self.layout["output_pagesize"][0] - (
             self.border_left + self.border_right
         )
-        printable_height = self.layout["pagesize"][1] - (
+        printable_height = self.layout["output_pagesize"][1] - (
             self.border_top + self.border_bottom
         )
 
@@ -92,20 +91,20 @@ class Plakativ:
                 # fit the input page size into the selected postersize
                 poster_width = self.config["postersize"][0]
                 poster_height = (
-                    poster_width * self.config["pagesize"][1]
-                ) / self.config["pagesize"][0]
+                    poster_width * self.config["input_pagesize"][1]
+                ) / self.config["input_pagesize"][0]
                 if poster_height > self.config["postersize"][1]:
                     poster_height = self.config["postersize"][1]
                     poster_width = (
-                        poster_height * self.config["pagesize"][0]
-                    ) / self.config["pagesize"][1]
+                        poster_height * self.config["input_pagesize"][0]
+                    ) / self.config["input_pagesize"][1]
             elif mode == "mult":
-                area = self.config["pagesize"][0] * self.config["pagesize"][1] * mult
+                area = self.config["input_pagesize"][0] * self.config["input_pagesize"][1] * mult
                 poster_width = math.sqrt(
-                    area * self.config["pagesize"][0] / self.config["pagesize"][1]
+                    area * self.config["input_pagesize"][0] / self.config["input_pagesize"][1]
                 )
                 poster_height = math.sqrt(
-                    area * self.config["pagesize"][1] / self.config["pagesize"][0]
+                    area * self.config["input_pagesize"][1] / self.config["input_pagesize"][0]
                 )
             else:
                 raise Exception("unsupported mode: %s" % mode)
@@ -153,13 +152,13 @@ class Plakativ:
 
                     poster_width = width_portrait
                     poster_height = (
-                        poster_width * self.config["pagesize"][1]
-                    ) / self.config["pagesize"][0]
+                        poster_width * self.config["input_pagesize"][1]
+                    ) / self.config["input_pagesize"][0]
                     if poster_height > height_portrait:
                         poster_height = height_portrait
                         poster_width = (
-                            poster_height * self.config["pagesize"][0]
-                        ) / self.config["pagesize"][1]
+                            poster_height * self.config["input_pagesize"][0]
+                        ) / self.config["input_pagesize"][1]
 
                     area_portrait = poster_width * poster_height
 
@@ -172,13 +171,13 @@ class Plakativ:
 
                     poster_width = width_landscape
                     poster_height = (
-                        poster_width * self.config["pagesize"][1]
-                    ) / self.config["pagesize"][0]
+                        poster_width * self.config["input_pagesize"][1]
+                    ) / self.config["input_pagesize"][0]
                     if poster_height > height_landscape:
                         poster_height = height_landscape
                         poster_width = (
-                            poster_height * self.config["pagesize"][0]
-                        ) / self.config["pagesize"][1]
+                            poster_height * self.config["input_pagesize"][0]
+                        ) / self.config["input_pagesize"][1]
 
                     area_landscape = poster_width * poster_height
 
@@ -215,7 +214,7 @@ class Plakativ:
         # return (self.postersize, (poster_width*poster_height)/(pt_to_mm(self.dlist.rect.width)*pt_to_mm(self.dlist.rect.height)), pages_x*pages_y)
         if mode == "size":
             self.config["mult"] = (poster_width * poster_height) / (
-                self.config["pagesize"][0] * self.config["pagesize"][1]
+                self.config["input_pagesize"][0] * self.config["input_pagesize"][1]
             )
             self.config["npages"] = pages_x * pages_y
         elif mode == "mult":
@@ -224,7 +223,7 @@ class Plakativ:
         elif mode == "npages":
             self.config["postersize"] = poster_width, poster_height
             self.config["mult"] = (poster_width * poster_height) / (
-                self.config["pagesize"][0] * self.config["pagesize"][1]
+                self.config["input_pagesize"][0] * self.config["input_pagesize"][1]
             )
         else:
             raise Exception("unsupported mode: %s" % mode)
@@ -239,11 +238,11 @@ class Plakativ:
 
         for (x, y, portrait) in self.layout["positions"]:
             if portrait:
-                page_width=mm_to_pt(self.layout["pagesize"][0])
-                page_height=mm_to_pt(self.layout["pagesize"][1])
+                page_width=mm_to_pt(self.layout["output_pagesize"][0])
+                page_height=mm_to_pt(self.layout["output_pagesize"][1])
             else:
-                page_width=mm_to_pt(self.layout["pagesize"][1])
-                page_height=mm_to_pt(self.layout["pagesize"][0])
+                page_width=mm_to_pt(self.layout["output_pagesize"][1])
+                page_height=mm_to_pt(self.layout["output_pagesize"][0])
             page = outdoc.newPage(
                 -1,  # insert after last page
                 width=page_width,
@@ -259,11 +258,11 @@ class Plakativ:
             target_xoffset = 0
             target_yoffset = 0
             if portrait:
-                target_width = self.layout["pagesize"][0]
-                target_height = self.layout["pagesize"][1]
+                target_width = self.layout["output_pagesize"][0]
+                target_height = self.layout["output_pagesize"][1]
             else:
-                target_width = self.layout["pagesize"][1]
-                target_height = self.layout["pagesize"][0]
+                target_width = self.layout["output_pagesize"][1]
+                target_height = self.layout["output_pagesize"][0]
             if target_x < 0:
                 target_xoffset = -target_x
                 target_width += target_x
@@ -284,8 +283,7 @@ class Plakativ:
                 mm_to_pt(target_yoffset + target_height),
             )
 
-            # FIXME: this should probably the pagesize of the input document instead
-            factor = self.layout["pagesize"][0] / self.layout["postersize"][0]
+            factor = self.config["input_pagesize"][0] / self.layout["postersize"][0]
             sourcerect = fitz.Rect(
                 mm_to_pt(factor * target_x),
                 mm_to_pt(factor * target_y),
@@ -735,11 +733,11 @@ class Application(tkinter.Frame):
                 - zoom_1 * self.plakativ.layout["overallsize"][1] / 2
             )
             if portrait:
-                x1 = x0 + self.plakativ.layout["pagesize"][0] * zoom_1
-                y1 = y0 + self.plakativ.layout["pagesize"][1] * zoom_1
+                x1 = x0 + self.plakativ.layout["output_pagesize"][0] * zoom_1
+                y1 = y0 + self.plakativ.layout["output_pagesize"][1] * zoom_1
             else:
-                x1 = x0 + self.plakativ.layout["pagesize"][1] * zoom_1
-                y1 = y0 + self.plakativ.layout["pagesize"][0] * zoom_1
+                x1 = x0 + self.plakativ.layout["output_pagesize"][1] * zoom_1
+                y1 = y0 + self.plakativ.layout["output_pagesize"][0] * zoom_1
             self.canvas.create_rectangle(x0, y0, x1, y1, outline="red")
             self.canvas.create_rectangle(
                 x0 + zoom_1 * self.border_left.get(),
diff --git a/test.py b/test.py
index fa30fbb..3f8b035 100644
--- a/test.py
+++ b/test.py
@@ -7,10 +7,46 @@ import os
 import pdfrw
 
 
+def mm_to_pt(length):
+    return (72.0 * length) / 25.4
+
+
+@pytest.fixture(scope="module")
+def infile_a4_portrait():
+    doc = fitz.open()
+    width = mm_to_pt(210)
+    height = mm_to_pt(297)
+    page = doc.newPage(pno=-1, width=width, height=height)
+    img = page.newShape()
+
+    red = fitz.utils.getColor("red")
+    green = fitz.utils.getColor("green")
+    blue = fitz.utils.getColor("blue")
+    orange = fitz.utils.getColor("orange")
+
+    img.insertText(fitz.Point(97, 620), "A", fontsize=600, color=blue)
+    img.commit()
+    img.drawLine(fitz.Point(0, 0), fitz.Point(width, height))
+    img.finish(color=red)
+    img.drawLine(fitz.Point(0, height), fitz.Point(width, 0))
+    img.finish(color=green)
+    img.drawRect(fitz.Rect(fitz.Point(0, 0), fitz.Point(width, height)))
+    img.finish(color=orange)
+    img.commit()
+
+    fd, tmpfile = tempfile.mkstemp(prefix="plakativ")
+    os.close(fd)
+    doc.save(tmpfile, pretty=True, expand=255)
+    yield tmpfile
+    os.unlink(tmpfile)
+
+
 @pytest.fixture(scope="module")
-def infile():
+def infile_a4_landscape():
     doc = fitz.open()
-    page = doc.newPage(pno=-1, width=595, height=842)
+    width = mm_to_pt(297)
+    height = mm_to_pt(210)
+    page = doc.newPage(pno=-1, width=width, height=height)
     img = page.newShape()
 
     red = fitz.utils.getColor("red")
@@ -20,11 +56,11 @@ def infile():
 
     img.insertText(fitz.Point(97, 620), "A", fontsize=600, color=blue)
     img.commit()
-    img.drawLine(fitz.Point(0, 0), fitz.Point(595, 842))
+    img.drawLine(fitz.Point(0, 0), fitz.Point(width, height))
     img.finish(color=red)
-    img.drawLine(fitz.Point(0, 842), fitz.Point(595, 0))
+    img.drawLine(fitz.Point(0, height), fitz.Point(width, 0))
     img.finish(color=green)
-    img.drawRect(fitz.Rect(fitz.Point(0, 0), fitz.Point(595, 842)))
+    img.drawRect(fitz.Rect(fitz.Point(0, 0), fitz.Point(width, height)))
     img.finish(color=orange)
     img.commit()
 
@@ -35,69 +71,132 @@ def infile():
     os.unlink(tmpfile)
 
 
-def test_foo(infile):
-    print("blob")
+def test_foo_a3_portrait(infile_a4_portrait):
     fd, outfile = tempfile.mkstemp(prefix="plakativ")
     os.close(fd)
-    plakativ.compute_layout(infile, outfile, mode="size", size=(297, 420))
+    plakativ.compute_layout(infile_a4_portrait, outfile, mode="size", size=(297, 420))
 
     reader = pdfrw.PdfReader(outfile)
+    os.unlink(outfile)
+
     pages = reader.Root.Pages.Kids
     assert len(pages) == 4
     assert pages[0].Resources.XObject.fzFrm0.BBox == [
         "0",
-        "380.6912",
-        "337.75163",
-        "842",
+        "380.8549",
+        "337.72779",
+        "841.8898",
     ]
     assert pages[1].Resources.XObject.fzFrm0.BBox == [
-        "257.524",
-        "380.6912",
-        "595",
-        "842",
+        "257.5478",
+        "380.8549",
+        "595.2756",
+        "841.8898",
     ]
     assert pages[2].Resources.XObject.fzFrm0.BBox == [
         "0",
         "0",
-        "337.75163",
-        "460.91883",
+        "337.72779",
+        "461.03489",
     ]
     assert pages[3].Resources.XObject.fzFrm0.BBox == [
-        "257.524",
+        "257.5478",
         "0",
-        "595",
-        "460.91883",
+        "595.2756",
+        "461.03489",
     ]
     assert pages[0].Resources.XObject.fzFrm0.Matrix == [
-        "1.4133016",
+        "1.4141413",
         "0",
         "0",
-        "1.4133016",
-        "117.930667",
-        "-538.03146",
+        "1.4141413",
+        "117.68077",
+        "-538.5826",
     ]
     assert pages[1].Resources.XObject.fzFrm0.Matrix == [
-        "1.4133017",
+        "1.4141413",
         "0",
         "0",
-        "1.4133017",
-        "-363.76438",
-        "-538.0315",
+        "1.4141413",
+        "-364.20893",
+        "-538.5826",
     ]
     assert pages[2].Resources.XObject.fzFrm0.Matrix == [
-        "1.4133016",
+        "1.4141413",
         "0",
         "0",
-        "1.4133016",
-        "117.930667",
-        "190.19687",
+        "1.4141413",
+        "117.68077",
+        "189.9213",
     ]
     assert pages[3].Resources.XObject.fzFrm0.Matrix == [
-        "1.4144558",
+        "1.4141413",
         "0",
         "0",
-        "1.4144558",
-        "-364.25627",
-        "189.93088",
+        "1.4141413",
+        "-364.20893",
+        "189.9213",
     ]
+
+
+def test_foo_a3_landscape(infile_a4_landscape):
+    fd, outfile = tempfile.mkstemp(prefix="plakativ")
+    os.close(fd)
+    plakativ.compute_layout(infile_a4_landscape, outfile, mode="size", size=(420, 296))
+
+    reader = pdfrw.PdfReader(outfile)
     os.unlink(outfile)
+
+    pages = reader.Root.Pages.Kids
+    assert len(pages) == 4
+    assert pages[0].Resources.XObject.fzFrm0.BBox == [
+        "0",
+        "257.41648",
+        "461.1662",
+        "595.2756",
+    ]
+    assert pages[1].Resources.XObject.fzFrm0.BBox == [
+        "380.72358",
+        "257.41648",
+        "841.8898",
+        "595.2756",
+    ]
+    assert pages[2].Resources.XObject.fzFrm0.BBox == ["0", "0", "461.1662", "337.8591"]
+    assert pages[3].Resources.XObject.fzFrm0.BBox == [
+        "380.72358",
+        "0",
+        "841.8898",
+        "337.8591",
+    ]
+    assert pages[0].Resources.XObject.fzFrm0.Matrix == [
+        "1.4095239",
+        "0",
+        "0",
+        "1.4095239",
+        "191.86499",
+        "-362.83467",
+    ]
+    assert pages[1].Resources.XObject.fzFrm0.Matrix == [
+        "1.4095239",
+        "0",
+        "0",
+        "1.4095239",
+        "-536.6389",
+        "-362.83467",
+    ]
+    assert pages[2].Resources.XObject.fzFrm0.Matrix == [
+        "1.4095239",
+        "0",
+        "0",
+        "1.4095239",
+        "191.86499",
+        "119.055118",
+    ]
+    assert pages[3].Resources.XObject.fzFrm0.Matrix == [
+        "1.4095239",
+        "0",
+        "0",
+        "1.4095239",
+        "-536.6389",
+        "119.055118",
+    ]