diff --git a/run b/run
index 81e3e3c..d9acf87 100755
--- a/run
+++ b/run
@@ -311,7 +311,7 @@ step11() {
 STEP12=f16c10a86b7183e99e54a70344f4681211cd52bb
 STEP12_=0.10.0-1506-gf16c10a86b
 step12() {
-  rm -fr "../zig-$STEP11"
+  rm -fr "../zig-$STEP12"
 
   # use the @qualCast implementation in src/, but remove usages in lib/
   git archive --prefix=zig-$STEP12_/ $STEP12 | tar -C .. -x
@@ -320,6 +320,30 @@ step12() {
     pushd "../zig-$STEP12_"
     cp ../zig-$STEP11_/stage1/zig1.wasm stage1/zig1.wasm
     fullbuild
+    build/stage3/bin/zig build --zig-lib-dir lib update-zig1
+    popd
+  }
+}
+
+# commit 7199d7c77715fe06606c5c89595e6852b3fa8c20
+# Author: Veikka Tuominen <git@vexu.eu>
+# Date:   2023-02-13T16:19:17+02:00
+#
+#     split `@qualCast` into `@constCast` and `@volatileCast`
+#
+STEP13=7199d7c77715fe06606c5c89595e6852b3fa8c20
+STEP13_=0.10.0-1638-g7199d7c777
+step13() {
+  rm -fr "../zig-$STEP13"
+
+  # ditto as previous step: implementation here, usages from HEAD~1
+  git archive --prefix=zig-$STEP13_/ $STEP13 | tar -C .. -x
+  git archive --prefix=zig-$STEP13_/ $STEP13~1 lib | tar -C .. -x
+  {
+    pushd "../zig-$STEP13_"
+    patch -p1 <"$HERE/0.10.0-1638-g7199d7c777-re-add-qualCast.patch"
+    ../zig-$STEP12_/build/stage3/bin/zig build --zig-lib-dir lib update-zig1
+    fullbuild
     popd
   }
 }
@@ -343,4 +367,5 @@ if [[ "${BASH_SOURCE[0]}" == "${0}" ]]; then
   if [[ "$step" -le 10 ]]; then step10; fi
   if [[ "$step" -le 11 ]]; then step11; fi
   if [[ "$step" -le 12 ]]; then step12; fi
+  if [[ "$step" -le 13 ]]; then step13; fi
 fi