diff --git a/dangerzone/conversion/errors.py b/dangerzone/conversion/errors.py
index a432e41..971f2da 100644
--- a/dangerzone/conversion/errors.py
+++ b/dangerzone/conversion/errors.py
@@ -24,6 +24,14 @@ class ConversionException(Exception):
         return subclasses
 
 
+class QubesNotEnoughRAMError(ConversionException):
+    error_code = 126  # No ERROR_SHIFT since this is a qrexec error
+    error_message = (
+        "Your system does not have enough RAM available to start the conversion. "
+        "Please close some qubes or programs and try again."
+    )
+
+
 class DocFormatUnsupported(ConversionException):
     error_code = ERROR_SHIFT + 10
     error_message = "The document format is not supported"
diff --git a/dangerzone/isolation_provider/qubes.py b/dangerzone/isolation_provider/qubes.py
index a762842..8c6429d 100644
--- a/dangerzone/isolation_provider/qubes.py
+++ b/dangerzone/isolation_provider/qubes.py
@@ -88,33 +88,13 @@ class Qubes(IsolationProvider):
         percentage = 0.0
 
         with open(document.input_filename, "rb") as f:
-            # TODO handle lack of memory to start qube
-            if getattr(sys, "dangerzone_dev", False):
-                # Use dz.ConvertDev RPC call instead, if we are in development mode.
-                # Basically, the change is that we also transfer the necessary Python
-                # code as a zipfile, before sending the doc that the user requested.
-                self.proc = subprocess.Popen(
-                    ["/usr/bin/qrexec-client-vm", "@dispvm:dz-dvm", "dz.ConvertDev"],
-                    stdin=subprocess.PIPE,
-                    stdout=subprocess.PIPE,
-                    stderr=subprocess.PIPE,
-                )
-                assert self.proc is not None
+            self.proc = self.qrexec_subprocess()
+            try:
                 assert self.proc.stdin is not None
-
-                # Send the dangerzone module first.
-                self.teleport_dz_module(self.proc.stdin)
-
-                # Finally, send the document, as in the normal case.
                 self.proc.stdin.write(f.read())
                 self.proc.stdin.close()
-            else:
-                self.proc = subprocess.Popen(
-                    ["/usr/bin/qrexec-client-vm", "@dispvm:dz-dvm", "dz.Convert"],
-                    stdin=f,
-                    stdout=subprocess.PIPE,
-                    stderr=subprocess.DEVNULL,
-                )
+            except BrokenPipeError as e:
+                raise errors.InterruptedConversion()
 
             # Get file size (in MiB)
             size = os.path.getsize(document.input_filename) / 1024**2
@@ -207,6 +187,32 @@ class Qubes(IsolationProvider):
     def get_max_parallel_conversions(self) -> int:
         return 1
 
+    def qrexec_subprocess(self) -> 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.
+            # Basically, the change is that we also transfer the necessary Python
+            # code as a zipfile, before sending the doc that the user requested.
+            qrexec_policy = "dz.ConvertDev"
+            stderr = subprocess.PIPE
+        else:
+            qrexec_policy = "dz.Convert"
+            stderr = subprocess.DEVNULL
+
+        p = subprocess.Popen(
+            ["/usr/bin/qrexec-client-vm", "@dispvm:dz-dvm", qrexec_policy],
+            stdin=subprocess.PIPE,
+            stdout=subprocess.PIPE,
+            stderr=stderr,
+        )
+
+        if dev_mode:
+            assert p.stdin is not None
+            # Send the dangerzone module first.
+            self.teleport_dz_module(p.stdin)
+
+        return p
+
     def teleport_dz_module(self, wpipe: IO[bytes]) -> None:
         """Send the dangerzone module to another qube, as a zipfile."""
         # Grab the absolute file path of the dangerzone module.
diff --git a/tests/isolation_provider/test_qubes.py b/tests/isolation_provider/test_qubes.py
index 45ac4d2..f8f6172 100644
--- a/tests/isolation_provider/test_qubes.py
+++ b/tests/isolation_provider/test_qubes.py
@@ -1,4 +1,9 @@
+import signal
+import subprocess
+import time
+
 import pytest
+from pytest import MonkeyPatch
 from pytest_mock import MockerFixture
 
 from dangerzone.conversion import errors
@@ -54,3 +59,30 @@ class TestQubes(IsolationProviderTest):
         with pytest.raises(errors.MaxPageHeightException):
             success = provider._convert(Document(sample_bad_height), ocr_lang=None)
             assert not success
+
+    def test_out_of_ram(
+        self,
+        provider: Qubes,
+        mocker: MockerFixture,
+        monkeypatch: MonkeyPatch,
+        sample_doc: str,
+    ) -> None:
+        provider.progress_callback = mocker.MagicMock()
+
+        def qrexec_subprocess() -> subprocess.Popen:
+            p = subprocess.Popen(
+                # XXX error 126 simulates a qrexec-policy failure. Source:
+                # https://github.com/QubesOS/qubes-core-qrexec/blob/fdcbfd7/daemon/qrexec-daemon.c#L1022
+                ["exit 126"],
+                stdin=subprocess.PIPE,
+                stdout=subprocess.PIPE,
+                stderr=subprocess.PIPE,
+                shell=True,
+            )
+            return p
+
+        monkeypatch.setattr(provider, "qrexec_subprocess", qrexec_subprocess)
+
+        with pytest.raises(errors.QubesNotEnoughRAMError) as e:
+            doc = Document(sample_doc)
+            provider._convert(doc, ocr_lang=None)