diff --git a/.basedpyright/baseline.json b/.basedpyright/baseline.json
index ed1954a0..bc6429b5 100644
--- a/.basedpyright/baseline.json
+++ b/.basedpyright/baseline.json
@@ -198,6 +198,24 @@
                 }
             }
         ],
+        "./examples/euler/acoustic_pulse.py": [
+            {
+                "code": "reportCallIssue",
+                "range": {
+                    "startColumn": 21,
+                    "endColumn": 51,
+                    "lineCount": 1
+                }
+            },
+            {
+                "code": "reportCallIssue",
+                "range": {
+                    "startColumn": 9,
+                    "endColumn": 39,
+                    "lineCount": 1
+                }
+            }
+        ],
         "./examples/hello-grudge.py": [
             {
                 "code": "reportPrivateLocalImportUsage",
@@ -206,9 +224,41 @@
                     "endColumn": 47,
                     "lineCount": 1
                 }
+            },
+            {
+                "code": "reportCallIssue",
+                "range": {
+                    "startColumn": 14,
+                    "endColumn": 38,
+                    "lineCount": 1
+                }
+            },
+            {
+                "code": "reportCallIssue",
+                "range": {
+                    "startColumn": 32,
+                    "endColumn": 55,
+                    "lineCount": 1
+                }
             }
         ],
         "./examples/wave/var-propagation-speed.py": [
+            {
+                "code": "reportCallIssue",
+                "range": {
+                    "startColumn": 17,
+                    "endColumn": 63,
+                    "lineCount": 1
+                }
+            },
+            {
+                "code": "reportCallIssue",
+                "range": {
+                    "startColumn": 22,
+                    "endColumn": 34,
+                    "lineCount": 1
+                }
+            },
             {
                 "code": "reportUnusedVariable",
                 "range": {
@@ -219,6 +269,14 @@
             }
         ],
         "./examples/wave/wave-min-mpi.py": [
+            {
+                "code": "reportCallIssue",
+                "range": {
+                    "startColumn": 17,
+                    "endColumn": 63,
+                    "lineCount": 1
+                }
+            },
             {
                 "code": "reportUnusedVariable",
                 "range": {
@@ -229,6 +287,14 @@
             }
         ],
         "./examples/wave/wave-op-mpi.py": [
+            {
+                "code": "reportCallIssue",
+                "range": {
+                    "startColumn": 13,
+                    "endColumn": 45,
+                    "lineCount": 1
+                }
+            },
             {
                 "code": "reportCallIssue",
                 "range": {
@@ -263,6 +329,30 @@
             }
         ],
         "./examples/wave/wave-op-var-velocity.py": [
+            {
+                "code": "reportCallIssue",
+                "range": {
+                    "startColumn": 12,
+                    "endColumn": 33,
+                    "lineCount": 1
+                }
+            },
+            {
+                "code": "reportCallIssue",
+                "range": {
+                    "startColumn": 23,
+                    "endColumn": 50,
+                    "lineCount": 1
+                }
+            },
+            {
+                "code": "reportCallIssue",
+                "range": {
+                    "startColumn": 13,
+                    "endColumn": 45,
+                    "lineCount": 1
+                }
+            },
             {
                 "code": "reportUnusedVariable",
                 "range": {
@@ -986,17 +1076,17 @@
             {
                 "code": "reportUnknownArgumentType",
                 "range": {
-                    "startColumn": 29,
-                    "endColumn": 45,
-                    "lineCount": 8
+                    "startColumn": 16,
+                    "endColumn": 17,
+                    "lineCount": 3
                 }
             },
             {
                 "code": "reportUnknownArgumentType",
                 "range": {
-                    "startColumn": 28,
-                    "endColumn": 44,
-                    "lineCount": 5
+                    "startColumn": 26,
+                    "endColumn": 61,
+                    "lineCount": 1
                 }
             },
             {
@@ -1358,10 +1448,18 @@
                 }
             },
             {
-                "code": "reportUnknownArgumentType",
+                "code": "reportUnknownVariableType",
                 "range": {
-                    "startColumn": 21,
-                    "endColumn": 29,
+                    "startColumn": 4,
+                    "endColumn": 11,
+                    "lineCount": 1
+                }
+            },
+            {
+                "code": "reportCallIssue",
+                "range": {
+                    "startColumn": 14,
+                    "endColumn": 38,
                     "lineCount": 1
                 }
             },
@@ -1774,10 +1872,18 @@
                 }
             },
             {
-                "code": "reportUnknownArgumentType",
+                "code": "reportUnknownVariableType",
                 "range": {
-                    "startColumn": 30,
-                    "endColumn": 36,
+                    "startColumn": 8,
+                    "endColumn": 20,
+                    "lineCount": 1
+                }
+            },
+            {
+                "code": "reportCallIssue",
+                "range": {
+                    "startColumn": 23,
+                    "endColumn": 45,
                     "lineCount": 1
                 }
             },
@@ -2230,13 +2336,21 @@
                 }
             },
             {
-                "code": "reportUnknownArgumentType",
+                "code": "reportCallIssue",
                 "range": {
-                    "startColumn": 23,
-                    "endColumn": 29,
+                    "startColumn": 16,
+                    "endColumn": 60,
                     "lineCount": 1
                 }
             },
+            {
+                "code": "reportUnknownArgumentType",
+                "range": {
+                    "startColumn": 16,
+                    "endColumn": 17,
+                    "lineCount": 16
+                }
+            },
             {
                 "code": "reportArgumentType",
                 "range": {
@@ -4609,6 +4723,14 @@
                     "lineCount": 1
                 }
             },
+            {
+                "code": "reportCallIssue",
+                "range": {
+                    "startColumn": 53,
+                    "endColumn": 84,
+                    "lineCount": 1
+                }
+            },
             {
                 "code": "reportUnknownMemberType",
                 "range": {
@@ -5155,6 +5277,14 @@
                     "lineCount": 1
                 }
             },
+            {
+                "code": "reportUnknownParameterType",
+                "range": {
+                    "startColumn": 8,
+                    "endColumn": 12,
+                    "lineCount": 1
+                }
+            },
             {
                 "code": "reportUnknownParameterType",
                 "range": {
@@ -5219,6 +5349,22 @@
                     "lineCount": 1
                 }
             },
+            {
+                "code": "reportUnknownVariableType",
+                "range": {
+                    "startColumn": 8,
+                    "endColumn": 25,
+                    "lineCount": 1
+                }
+            },
+            {
+                "code": "reportCallIssue",
+                "range": {
+                    "startColumn": 16,
+                    "endColumn": 37,
+                    "lineCount": 1
+                }
+            },
             {
                 "code": "reportUnknownMemberType",
                 "range": {
@@ -5243,6 +5389,22 @@
                     "lineCount": 1
                 }
             },
+            {
+                "code": "reportUnknownVariableType",
+                "range": {
+                    "startColumn": 19,
+                    "endColumn": 36,
+                    "lineCount": 1
+                }
+            },
+            {
+                "code": "reportUnknownVariableType",
+                "range": {
+                    "startColumn": 19,
+                    "endColumn": 63,
+                    "lineCount": 3
+                }
+            },
             {
                 "code": "reportUnknownMemberType",
                 "range": {
@@ -5259,6 +5421,14 @@
                     "lineCount": 1
                 }
             },
+            {
+                "code": "reportCallIssue",
+                "range": {
+                    "startColumn": 34,
+                    "endColumn": 61,
+                    "lineCount": 1
+                }
+            },
             {
                 "code": "reportArgumentType",
                 "range": {
@@ -5435,6 +5605,14 @@
                     "lineCount": 1
                 }
             },
+            {
+                "code": "reportCallIssue",
+                "range": {
+                    "startColumn": 35,
+                    "endColumn": 60,
+                    "lineCount": 1
+                }
+            },
             {
                 "code": "reportArgumentType",
                 "range": {
@@ -5443,6 +5621,14 @@
                     "lineCount": 1
                 }
             },
+            {
+                "code": "reportCallIssue",
+                "range": {
+                    "startColumn": 28,
+                    "endColumn": 53,
+                    "lineCount": 1
+                }
+            },
             {
                 "code": "reportArgumentType",
                 "range": {
@@ -5451,6 +5637,14 @@
                     "lineCount": 1
                 }
             },
+            {
+                "code": "reportUnknownParameterType",
+                "range": {
+                    "startColumn": 12,
+                    "endColumn": 16,
+                    "lineCount": 1
+                }
+            },
             {
                 "code": "reportUnknownParameterType",
                 "range": {
@@ -5467,6 +5661,14 @@
                     "lineCount": 1
                 }
             },
+            {
+                "code": "reportUnknownVariableType",
+                "range": {
+                    "startColumn": 19,
+                    "endColumn": 77,
+                    "lineCount": 1
+                }
+            },
             {
                 "code": "reportUnknownMemberType",
                 "range": {
@@ -5971,6 +6173,14 @@
                     "lineCount": 1
                 }
             },
+            {
+                "code": "reportUnknownParameterType",
+                "range": {
+                    "startColumn": 8,
+                    "endColumn": 12,
+                    "lineCount": 1
+                }
+            },
             {
                 "code": "reportUnknownParameterType",
                 "range": {
@@ -6043,6 +6253,22 @@
                     "lineCount": 1
                 }
             },
+            {
+                "code": "reportUnknownVariableType",
+                "range": {
+                    "startColumn": 8,
+                    "endColumn": 25,
+                    "lineCount": 1
+                }
+            },
+            {
+                "code": "reportCallIssue",
+                "range": {
+                    "startColumn": 12,
+                    "endColumn": 53,
+                    "lineCount": 1
+                }
+            },
             {
                 "code": "reportUnknownMemberType",
                 "range": {
@@ -6115,6 +6341,22 @@
                     "lineCount": 1
                 }
             },
+            {
+                "code": "reportUnknownVariableType",
+                "range": {
+                    "startColumn": 19,
+                    "endColumn": 36,
+                    "lineCount": 1
+                }
+            },
+            {
+                "code": "reportUnknownVariableType",
+                "range": {
+                    "startColumn": 19,
+                    "endColumn": 77,
+                    "lineCount": 4
+                }
+            },
             {
                 "code": "reportUnknownMemberType",
                 "range": {
@@ -6147,6 +6389,14 @@
                     "lineCount": 1
                 }
             },
+            {
+                "code": "reportCallIssue",
+                "range": {
+                    "startColumn": 29,
+                    "endColumn": 76,
+                    "lineCount": 1
+                }
+            },
             {
                 "code": "reportArgumentType",
                 "range": {
@@ -6411,6 +6661,14 @@
                     "lineCount": 1
                 }
             },
+            {
+                "code": "reportCallIssue",
+                "range": {
+                    "startColumn": 36,
+                    "endColumn": 61,
+                    "lineCount": 1
+                }
+            },
             {
                 "code": "reportArgumentType",
                 "range": {
@@ -6419,6 +6677,14 @@
                     "lineCount": 1
                 }
             },
+            {
+                "code": "reportCallIssue",
+                "range": {
+                    "startColumn": 28,
+                    "endColumn": 53,
+                    "lineCount": 1
+                }
+            },
             {
                 "code": "reportArgumentType",
                 "range": {
@@ -6427,6 +6693,14 @@
                     "lineCount": 1
                 }
             },
+            {
+                "code": "reportUnknownParameterType",
+                "range": {
+                    "startColumn": 12,
+                    "endColumn": 16,
+                    "lineCount": 1
+                }
+            },
             {
                 "code": "reportUnknownParameterType",
                 "range": {
@@ -6443,6 +6717,14 @@
                     "lineCount": 1
                 }
             },
+            {
+                "code": "reportUnknownVariableType",
+                "range": {
+                    "startColumn": 19,
+                    "endColumn": 77,
+                    "lineCount": 1
+                }
+            },
             {
                 "code": "reportUnknownMemberType",
                 "range": {
@@ -6613,54 +6895,6 @@
                     "lineCount": 1
                 }
             },
-            {
-                "code": "reportUnknownArgumentType",
-                "range": {
-                    "startColumn": 28,
-                    "endColumn": 71,
-                    "lineCount": 1
-                }
-            },
-            {
-                "code": "reportUnknownMemberType",
-                "range": {
-                    "startColumn": 29,
-                    "endColumn": 35,
-                    "lineCount": 1
-                }
-            },
-            {
-                "code": "reportUnknownMemberType",
-                "range": {
-                    "startColumn": 38,
-                    "endColumn": 44,
-                    "lineCount": 1
-                }
-            },
-            {
-                "code": "reportUnknownVariableType",
-                "range": {
-                    "startColumn": 8,
-                    "endColumn": 18,
-                    "lineCount": 1
-                }
-            },
-            {
-                "code": "reportUnknownMemberType",
-                "range": {
-                    "startColumn": 21,
-                    "endColumn": 42,
-                    "lineCount": 1
-                }
-            },
-            {
-                "code": "reportUnknownArgumentType",
-                "range": {
-                    "startColumn": 20,
-                    "endColumn": 30,
-                    "lineCount": 1
-                }
-            },
             {
                 "code": "reportCallIssue",
                 "range": {
@@ -6685,30 +6919,6 @@
                     "lineCount": 1
                 }
             },
-            {
-                "code": "reportUnknownVariableType",
-                "range": {
-                    "startColumn": 8,
-                    "endColumn": 18,
-                    "lineCount": 1
-                }
-            },
-            {
-                "code": "reportUnknownMemberType",
-                "range": {
-                    "startColumn": 21,
-                    "endColumn": 42,
-                    "lineCount": 1
-                }
-            },
-            {
-                "code": "reportUnknownArgumentType",
-                "range": {
-                    "startColumn": 62,
-                    "endColumn": 72,
-                    "lineCount": 1
-                }
-            },
             {
                 "code": "reportCallIssue",
                 "range": {
@@ -8203,78 +8413,6 @@
                     "lineCount": 3
                 }
             },
-            {
-                "code": "reportUnknownVariableType",
-                "range": {
-                    "startColumn": 16,
-                    "endColumn": 19,
-                    "lineCount": 1
-                }
-            },
-            {
-                "code": "reportUnknownVariableType",
-                "range": {
-                    "startColumn": 16,
-                    "endColumn": 34,
-                    "lineCount": 1
-                }
-            },
-            {
-                "code": "reportUnknownMemberType",
-                "range": {
-                    "startColumn": 37,
-                    "endColumn": 56,
-                    "lineCount": 1
-                }
-            },
-            {
-                "code": "reportUnknownArgumentType",
-                "range": {
-                    "startColumn": 31,
-                    "endColumn": 49,
-                    "lineCount": 1
-                }
-            },
-            {
-                "code": "reportUnknownVariableType",
-                "range": {
-                    "startColumn": 20,
-                    "endColumn": 38,
-                    "lineCount": 1
-                }
-            },
-            {
-                "code": "reportUnknownMemberType",
-                "range": {
-                    "startColumn": 41,
-                    "endColumn": 60,
-                    "lineCount": 1
-                }
-            },
-            {
-                "code": "reportUnknownMemberType",
-                "range": {
-                    "startColumn": 54,
-                    "endColumn": 78,
-                    "lineCount": 1
-                }
-            },
-            {
-                "code": "reportUnknownArgumentType",
-                "range": {
-                    "startColumn": 54,
-                    "endColumn": 78,
-                    "lineCount": 1
-                }
-            },
-            {
-                "code": "reportUnknownVariableType",
-                "range": {
-                    "startColumn": 24,
-                    "endColumn": 27,
-                    "lineCount": 1
-                }
-            },
             {
                 "code": "reportRedeclaration",
                 "range": {
@@ -8346,14 +8484,6 @@
                     "endColumn": 29,
                     "lineCount": 1
                 }
-            },
-            {
-                "code": "reportUnknownVariableType",
-                "range": {
-                    "startColumn": 45,
-                    "endColumn": 48,
-                    "lineCount": 1
-                }
             }
         ],
         "./grudge/trace_pair.py": [
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 292754a8..25254cb1 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -31,7 +31,7 @@ jobs:
                 curl -L -O https://tiker.net/ci-support-v0
                 . ./ci-support-v0
                 build_py_project_in_conda_env
-                cipip install pytest modepy 'optype<0.18'
+                cipip install pytest modepy optype
                 cipip install basedpyright
                 basedpyright
 
diff --git a/pyproject.toml b/pyproject.toml
index 5906b6c1..45b29374 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -55,8 +55,7 @@ test = [
     "basedpyright",
     "pytest",
     "ruff",
-    # NOTE: 0.18 requires Python 3.12
-    "optype<0.18",
+    "optype",
 ]
 
 [project.urls]
@@ -163,7 +162,7 @@ exclude = [
     ".venv",
 ]
 
-pythonVersion = "3.10"
+pythonVersion = "3.12"
 pythonPlatform = "All"