diff --git a/cubed/core/plan.py b/cubed/core/plan.py
index 6eda28059..6c816c594 100644
--- a/cubed/core/plan.py
+++ b/cubed/core/plan.py
@@ -268,6 +268,26 @@ def _compile_blockwise(self, dag, compile_function: Decorator) -> nx.MultiDiGrap
 
         return dag
 
+    def _check_projected_mem(self, dag) -> None:
+        op_name = None
+        max_projected_mem_op = None
+        for n, d in dag.nodes(data=True):
+            if "primitive_op" in d:
+                op = d["primitive_op"]
+                if (
+                    max_projected_mem_op is None
+                    or op.projected_mem > max_projected_mem_op.projected_mem
+                ):
+                    op_name = n
+                    max_projected_mem_op = op
+        if max_projected_mem_op is not None:
+            op = max_projected_mem_op
+            if op.projected_mem > op.allowed_mem:
+                raise ValueError(
+                    f"Projected blockwise memory ({memory_repr(op.projected_mem)}) exceeds allowed_mem ({memory_repr(op.allowed_mem)}), "
+                    f"including reserved_mem ({memory_repr(op.reserved_mem)}) for {op_name}"
+                )
+
     @lru_cache  # noqa: B019
     def _finalize(
         self,
@@ -281,6 +301,7 @@ def _finalize(
         if callable(compile_function):
             dag = self._compile_blockwise(dag, compile_function)
         dag = self._create_lazy_zarr_arrays(dag)
+        self._check_projected_mem(dag)
         return FinalizedPlan(nx.freeze(dag), self.array_names, optimize_graph)
 
 
diff --git a/cubed/primitive/blockwise.py b/cubed/primitive/blockwise.py
index 905e32e03..ed2f2dcfe 100644
--- a/cubed/primitive/blockwise.py
+++ b/cubed/primitive/blockwise.py
@@ -413,11 +413,6 @@ def general_blockwise(
         buffer_copies=buffer_copies,
     )
 
-    if projected_mem > allowed_mem:
-        raise ValueError(
-            f"Projected blockwise memory ({projected_mem}) exceeds allowed_mem ({allowed_mem}), including reserved_mem ({reserved_mem})"
-        )
-
     # this must be an iterator of lists, not of tuples, otherwise lithops breaks
     if output_blocks is None:
         output_blocks = map(
diff --git a/cubed/tests/primitive/test_blockwise.py b/cubed/tests/primitive/test_blockwise.py
index b4e9a8837..337295c61 100644
--- a/cubed/tests/primitive/test_blockwise.py
+++ b/cubed/tests/primitive/test_blockwise.py
@@ -149,25 +149,23 @@ def test_blockwise_allowed_mem_exceeded(tmp_path, reserved_mem):
     allowed_mem = 100
     target_store = tmp_path / "target.zarr"
 
-    with pytest.raises(
-        ValueError,
-        match=r"Projected blockwise memory \(\d+\) exceeds allowed_mem \(100\), including reserved_mem \(\d+\)",
-    ):
-        blockwise(
-            nxp.linalg.outer,
-            "ij",
-            source1,
-            "i",
-            source2,
-            "j",
-            allowed_mem=allowed_mem,
-            reserved_mem=reserved_mem,
-            target_store=target_store,
-            target_name="target",
-            shape=(3, 3),
-            dtype=np.int64,
-            chunks=(2, 2),
-        )
+    op = blockwise(
+        nxp.linalg.outer,
+        "ij",
+        source1,
+        "i",
+        source2,
+        "j",
+        allowed_mem=allowed_mem,
+        reserved_mem=reserved_mem,
+        target_store=target_store,
+        target_name="target",
+        shape=(3, 3),
+        dtype=np.int64,
+        chunks=(2, 2),
+    )
+
+    assert op.projected_mem > op.allowed_mem
 
 
 def test_general_blockwise(tmp_path, executor):
diff --git a/cubed/tests/test_core.py b/cubed/tests/test_core.py
index 2ae72ab8f..89ab0a6d3 100644
--- a/cubed/tests/test_core.py
+++ b/cubed/tests/test_core.py
@@ -491,11 +491,12 @@ def test_default_spec(executor):
 def test_default_spec_allowed_mem_exceeded():
     # default spec fails for large computations
     a = xp.ones((20000, 10000), chunks=(10000, 10000))
+    b = xp.negative(a)
     with pytest.raises(
         ValueError,
-        match=r"Projected blockwise memory \(\d+\) exceeds allowed_mem \(\d+\), including reserved_mem \(\d+\)",
+        match=r"Projected blockwise memory \(.+\) exceeds allowed_mem \(.+\), including reserved_mem \(.+\) for op-\d+",
     ):
-        xp.negative(a)
+        b.plan()
 
 
 def test_default_spec_config_override():