diff --git a/document/core/Makefile b/document/core/Makefile
index a7e3c8529a..df245c881c 100644
--- a/document/core/Makefile
+++ b/document/core/Makefile
@@ -12,7 +12,7 @@ DOWNLOADDIR   = _download
 NAME          = WebAssembly
 DECISION_URL  = https://github.com/WebAssembly/meetings/blob/main/main/2024/WG-06-12.md
 TAR           = tar
-DEADLINE      = $(shell python3 ../deadline.py)
+DEADLINE      = $(shell date -d "+30 days" +%Y-%m-%d 2>/dev/null || date -v +30d +%Y-%m-%d)
 
 # Internal variables.
 PAPEROPT_a4     = -D latex_paper_size=a4
diff --git a/document/deadline.py b/document/deadline.py
deleted file mode 100755
index 9fec73181d..0000000000
--- a/document/deadline.py
+++ /dev/null
@@ -1,4 +0,0 @@
-#!/usr/bin/env python3
-import datetime
-
-print(datetime.date.today() + datetime.timedelta(days=30))
diff --git a/document/js-api/Makefile b/document/js-api/Makefile
index 02d97de02f..7893918d46 100644
--- a/document/js-api/Makefile
+++ b/document/js-api/Makefile
@@ -5,7 +5,7 @@ DOWNLOADDIR   = _download
 NAME          = WebAssembly
 DECISION_URL  = https://github.com/WebAssembly/meetings/blob/main/main/2024/WG-06-12.md
 TAR           = tar
-DEADLINE      = $(shell python3 ../deadline.py)
+DEADLINE      = $(shell date -d "+30 days" +%Y-%m-%d 2>/dev/null || date -v +30d +%Y-%m-%d)
 
 .PHONY: all
 all:
diff --git a/document/web-api/Makefile b/document/web-api/Makefile
index 2a9eb9c748..2ea8f11ac5 100644
--- a/document/web-api/Makefile
+++ b/document/web-api/Makefile
@@ -5,7 +5,7 @@ DOWNLOADDIR   = _download
 NAME          = WebAssembly
 DECISION_URL  = https://github.com/WebAssembly/meetings/blob/main/main/2024/WG-06-12.md
 TAR           = tar
-DEADLINE      = $(shell python3 ../deadline.py)
+DEADLINE      = $(shell date -d "+30 days" +%Y-%m-%d 2>/dev/null || date -v +30d +%Y-%m-%d)
 
 .PHONY: all
 all: