diff --git a/dangerzone/isolation_provider/base.py b/dangerzone/isolation_provider/base.py
index d378eee..b8bc3c0 100644
--- a/dangerzone/isolation_provider/base.py
+++ b/dangerzone/isolation_provider/base.py
@@ -69,7 +69,7 @@ class IsolationProvider(ABC):
         self.progress_callback = progress_callback
         document.mark_as_converting()
         try:
-            conversion_proc = self.start_doc_to_pixels_proc()
+            conversion_proc = self.start_doc_to_pixels_proc(document)
             with tempfile.TemporaryDirectory() as t:
                 Path(f"{t}/pixels").mkdir()
                 self.doc_to_pixels(document, t, conversion_proc)
@@ -192,7 +192,7 @@ class IsolationProvider(ABC):
         return armor_start + conversion_string + armor_end
 
     @abstractmethod
-    def start_doc_to_pixels_proc(self) -> subprocess.Popen:
+    def start_doc_to_pixels_proc(self, document: Document) -> subprocess.Popen:
         pass
 
 
diff --git a/dangerzone/isolation_provider/container.py b/dangerzone/isolation_provider/container.py
index cbadcc3..ef5dd91 100644
--- a/dangerzone/isolation_provider/container.py
+++ b/dangerzone/isolation_provider/container.py
@@ -251,7 +251,7 @@ class Container(IsolationProvider):
             )
             shutil.move(container_output_filename, document.output_filename)
 
-    def start_doc_to_pixels_proc(self) -> subprocess.Popen:
+    def start_doc_to_pixels_proc(self, document: Document) -> subprocess.Popen:
         # Convert document to pixels
         command = [
             "/usr/bin/python3",
diff --git a/dangerzone/isolation_provider/dummy.py b/dangerzone/isolation_provider/dummy.py
index fa671f1..af5a263 100644
--- a/dangerzone/isolation_provider/dummy.py
+++ b/dangerzone/isolation_provider/dummy.py
@@ -74,7 +74,7 @@ class Dummy(IsolationProvider):
     ) -> None:
         pass
 
-    def start_doc_to_pixels_proc(self) -> subprocess.Popen:
+    def start_doc_to_pixels_proc(self, document: Document) -> subprocess.Popen:
         return subprocess.Popen("True")
 
     def get_max_parallel_conversions(self) -> int:
diff --git a/dangerzone/isolation_provider/qubes.py b/dangerzone/isolation_provider/qubes.py
index 0b607f8..b26d390 100644
--- a/dangerzone/isolation_provider/qubes.py
+++ b/dangerzone/isolation_provider/qubes.py
@@ -51,7 +51,7 @@ class Qubes(IsolationProvider):
     def get_max_parallel_conversions(self) -> int:
         return 1
 
-    def start_doc_to_pixels_proc(self) -> subprocess.Popen:
+    def start_doc_to_pixels_proc(self, document: Document) -> subprocess.Popen:
         dev_mode = getattr(sys, "dangerzone_dev", False) == True
         if dev_mode:
             # Use dz.ConvertDev RPC call instead, if we are in development mode.
diff --git a/tests/isolation_provider/base.py b/tests/isolation_provider/base.py
index 2640773..ac7cc97 100644
--- a/tests/isolation_provider/base.py
+++ b/tests/isolation_provider/base.py
@@ -37,7 +37,7 @@ class IsolationProviderTest:
         provider.progress_callback = mocker.MagicMock()
         doc = Document(pdf_11k_pages)
 
-        p = provider.start_doc_to_pixels_proc()
+        p = provider.start_doc_to_pixels_proc(doc)
         with pytest.raises(errors.ConverterProcException):
             provider.doc_to_pixels(doc, tmpdir, p)
             assert provider.get_proc_exception(p) == errors.MaxPagesException
@@ -54,7 +54,7 @@ class IsolationProviderTest:
             "dangerzone.conversion.errors.MAX_PAGES", 1
         )  # sample_doc has 4 pages > 1
         doc = Document(sample_doc)
-        p = provider.start_doc_to_pixels_proc()
+        p = provider.start_doc_to_pixels_proc(doc)
         with pytest.raises(errors.MaxPagesException):
             provider.doc_to_pixels(doc, tmpdir, p)
 
@@ -67,10 +67,12 @@ class IsolationProviderTest:
         tmpdir: str,
     ) -> None:
         provider.progress_callback = mocker.MagicMock()
-        p = provider.start_doc_to_pixels_proc()
+        doc = Document(sample_bad_width)
+        p = provider.start_doc_to_pixels_proc(doc)
         with pytest.raises(errors.MaxPageWidthException):
-            provider.doc_to_pixels(Document(sample_bad_width), tmpdir, p)
+            provider.doc_to_pixels(doc, tmpdir, p)
 
-        p = provider.start_doc_to_pixels_proc()
+        doc = Document(sample_bad_height)
+        p = provider.start_doc_to_pixels_proc(doc)
         with pytest.raises(errors.MaxPageHeightException):
-            provider.doc_to_pixels(Document(sample_bad_height), tmpdir, p)
+            provider.doc_to_pixels(doc, tmpdir, p)