diff --git a/.github/workflows/wai-quantum-metal.yml b/.github/workflows/wai-quantum-metal.yml
index ab5ddfc2b..2e33cfcad 100644
--- a/.github/workflows/wai-quantum-metal.yml
+++ b/.github/workflows/wai-quantum-metal.yml
@@ -53,7 +53,10 @@ jobs:
     name: member · Metal (macos)
     needs: relevant
     if: needs.relevant.outputs.run == 'true'
-    runs-on: macos
+    # The pins are the Mac Studio's GPU (gpu-msl-1009). The fleet's other macOS runners
+    # (an M4 Max and an M5 Max) have other GPUs, so this member runs on the Studio by its
+    # own label; a member for theirs is declared from a run on them.
+    runs-on: macos-m3-ultra
     timeout-minutes: 90
     env:
       WAI_QUANTUM_METAL_EXPECT: gpu-msl-1009
diff --git a/.github/workflows/wai-quantum-sme.yml b/.github/workflows/wai-quantum-sme.yml
index abcf92018..4269bcc77 100644
--- a/.github/workflows/wai-quantum-sme.yml
+++ b/.github/workflows/wai-quantum-sme.yml
@@ -114,7 +114,9 @@ jobs:
     name: member · matrix extension absent (macos)
     needs: relevant
     if: needs.relevant.outputs.run == 'true'
-    runs-on: macos
+    # The Mac Studio's M3 Ultra has no matrix extension; the fleet's M4 Max and M5 Max
+    # do, and this member refuses a host that has one. It runs on the Studio by its label.
+    runs-on: macos-m3-ultra
     timeout-minutes: 60
     env:
       WAI_QUANTUM_SME_EXPECT: none