diff --git a/src/lembas/__init__.py b/src/lembas/__init__.py
index b2fe638..d130a77 100644
--- a/src/lembas/__init__.py
+++ b/src/lembas/__init__.py
@@ -1,3 +1,3 @@
 """LLeMbas - a Middle-earth themed web UI for OpenAI-compatible LLM endpoints."""
 
-__version__ = "0.7.0"
+__version__ = "0.7.1"
diff --git a/src/lembas/services/images/tool.py b/src/lembas/services/images/tool.py
index 59f0c92..89a961f 100644
--- a/src/lembas/services/images/tool.py
+++ b/src/lembas/services/images/tool.py
@@ -75,7 +75,10 @@ SCHEMA: dict[str, Any] = {
         },
         "seed": {
             "type": "integer",
-            "description": "Omit for a new random image; repeat one to get the same image again.",
+            "description": (
+                "Omit it, or pass -1, for a new random image. Repeat a seed you were "
+                "told about to get the same image again."
+            ),
         },
         "steps": {"type": "integer", "description": "Sampling steps. Default 20."},
         "cfg": {"type": "number", "description": "Prompt adherence. Default 8."},
diff --git a/src/lembas/services/images/workflow.py b/src/lembas/services/images/workflow.py
index 9f8cb89..3b47ecc 100644
--- a/src/lembas/services/images/workflow.py
+++ b/src/lembas/services/images/workflow.py
@@ -86,13 +86,21 @@ def resolve(given: dict[str, Any]) -> dict[str, Any]:
     Absent and null are both "no opinion". A model that emits `"seed": null`
     rather than omitting the key is common enough that treating it as a request
     for seed zero would be a bug nobody could see.
+
+    **A negative seed means random**, which is what `-1` means in ComfyUI's own
+    interface, in A1111, and in every other thing that has ever asked somebody
+    for a seed. A model that has read any of them will write it, and without
+    this it went through the uint64 wrap and came out as 18446744073709551615 --
+    a perfectly valid *fixed* seed, so "give me something new" produced the same
+    picture every time. Exactly the wrong answer, arrived at silently.
     """
     values: dict[str, Any] = {**DEFAULTS}
     for name, value in (given or {}).items():
         if name in PLACEHOLDERS and value is not None and value != "":
             values[name] = value
 
-    values["seed"] = _whole(values.get("seed"), default=random_seed()) % (MAX_SEED + 1)
+    seed = _whole(values.get("seed"), default=-1)
+    values["seed"] = random_seed() if seed < 0 else seed % (MAX_SEED + 1)
     for name in ("steps", "width", "height"):
         values[name] = _clamp(_whole(values.get(name), DEFAULTS[name]), name)
     for name in ("cfg", "denoise"):
diff --git a/tests/test_images_workflow.py b/tests/test_images_workflow.py
index ed83efa..ac1d44e 100644
--- a/tests/test_images_workflow.py
+++ b/tests/test_images_workflow.py
@@ -96,6 +96,27 @@ def test_a_named_seed_is_kept():
     assert wf.resolve({"prompt": "x", "seed": 1234})["seed"] == 1234
 
 
+@pytest.mark.parametrize("sentinel", [-1, -5, "-1"])
+def test_a_negative_seed_means_random(sentinel):
+    """`-1` is what ComfyUI's own interface, A1111 and everything else that has
+    ever asked for a seed use for "surprise me", so a model that has read any of
+    them will write it.
+
+    Without this it went through the uint64 wrap and came out as
+    18446744073709551615 -- a perfectly valid *fixed* seed, so asking for
+    something new produced the same picture every time.
+    """
+    seeds = {wf.resolve({"prompt": "x", "seed": sentinel})["seed"] for _ in range(8)}
+    assert len(seeds) == 8
+    assert all(0 <= seed <= wf.MAX_SEED for seed in seeds)
+
+
+def test_seed_zero_is_a_real_seed():
+    """It is the boundary the negative test could easily have swallowed, and
+    zero is a seed somebody deliberately picks."""
+    assert wf.resolve({"prompt": "x", "seed": 0})["seed"] == 0
+
+
 @pytest.mark.parametrize("empty", [None, ""])
 def test_null_and_empty_mean_no_opinion(empty):
     """A model that emits `"steps": null` rather than omitting the key is common