diff --git a/run b/run
index b9adf9a..2839f3f 100755
--- a/run
+++ b/run
@@ -872,6 +872,68 @@ step37() {
   }
 }
 
+# commit 21780899eb17a0cb795ff40e5fae6556c38ea13e
+# Author: Andrew Kelley <andrew@ziglang.org>
+# Date:   2023-09-27T21:21:59+03:00
+#
+#     compiler: don't use `@abs` builtin yet
+#
+#     This commit can be used to rebuild zig1.wasm
+#
+STEP38=21780899eb17a0cb795ff40e5fae6556c38ea13e
+STEP38_=0.11.0-631-g21780899eb
+step38() {
+  rm -fr "../zig-$STEP38_"
+  git archive --prefix=zig-$STEP38_/ $STEP38 | tar -C .. -x
+  {
+    pushd "../zig-$STEP38_"
+    cp ../zig-$STEP37_/stage1/zig1.wasm stage1/zig1.wasm
+    halfbuild 17
+    popd
+  }
+}
+
+# commit 9763573ebb4f05eaa1c0bd5598f8dd6aee20ae9c
+# Author: Andrew Kelley <andrew@ziglang.org>
+# Date:   2023-09-27T21:28:47+03:00
+#
+#     update zig1.wasm
+#
+#     Needed because the compiler used the now removed `@fabs` builtin and
+#     instead depends on the new `@abs` builtin.
+#
+STEP39=9763573ebb4f05eaa1c0bd5598f8dd6aee20ae9c
+STEP39_=0.11.0-638-g9763573ebb
+step39() {
+  rm -fr "../zig-$STEP39_"
+  git archive --prefix=zig-$STEP39_/ $STEP39 | tar -C .. -x
+  {
+    pushd "../zig-$STEP39_"
+    ../zig-$STEP38_/build/zig2 build --zig-lib-dir lib update-zig1
+    halfbuild 17
+    popd
+  }
+}
+
+# commit 63bd2bff12992aef0ce23ae4b344e9cb5d65f05d
+# Author: Veikka Tuominen <git@vexu.eu>
+# Date:   2023-10-01T13:16:02+03:00
+#
+#     Sema: add `@errorCast` which works for both error sets and error unions
+#
+STEP40=63bd2bff12992aef0ce23ae4b344e9cb5d65f05d
+STEP40_=0.11.0-702-g63bd2bff12
+step40() {
+  rm -fr "../zig-$STEP40_"
+  git archive --prefix=zig-$STEP40_/ $STEP40 | tar -C .. -x
+  {
+    pushd "../zig-$STEP40_"
+    ../zig-$STEP39_/build/zig2 build update-zig1
+    popd
+  }
+}
+
+
 if [[ "${BASH_SOURCE[0]}" == "${0}" ]]; then
   set -xeuo pipefail
   step=${1:-step00}
@@ -916,4 +978,7 @@ if [[ "${BASH_SOURCE[0]}" == "${0}" ]]; then
   if [[ "$step" -le 35 ]]; then step35; fi
   if [[ "$step" -le 36 ]]; then step36; fi
   if [[ "$step" -le 37 ]]; then step37; fi
+  if [[ "$step" -le 38 ]]; then step38; fi
+  if [[ "$step" -le 39 ]]; then step39; fi
+  if [[ "$step" -le 40 ]]; then step40; fi
 fi