diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index cf4a3fae..7b96b148 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -29,7 +29,7 @@ jobs:
         -   name: "Main Script"
             run: |
                 EXTRA_INSTALL="pytest git+https://github.com/inducer/loopy.git \
-                    git+https://github.com/inducer/sumpy.git optype"
+                    git+https://github.com/inducer/sumpy.git optype<0.18"
                 curl -L -O https://tiker.net/ci-support-v0
                 . ./ci-support-v0
 
diff --git a/pyproject.toml b/pyproject.toml
index 0881c15a..e909fb76 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -53,6 +53,8 @@ meshmode = [
 test = [
     "pytest",
     "ruff",
+    # NOTE: 0.18 requires Python 3.12
+    "optype<0.18",
 ]
 
 [project.urls]