diff --git a/data/special-requirements b/data/special-requirements
index 9b63b33..45e2cef 100644
--- a/data/special-requirements
+++ b/data/special-requirements
@@ -13,3 +13,4 @@ simdjson !jessie !stretch
 sodium !jessie
 sqlsrv !7.1-alpine3.9 !7.1-alpine3.10 !arm
 vips !alpine3.9 !jessie
+wikidiff2 !jessie !stretch
diff --git a/data/supported-extensions b/data/supported-extensions
index 5fe54b5..ae1835f 100644
--- a/data/supported-extensions
+++ b/data/supported-extensions
@@ -128,6 +128,7 @@ uv 8.0 8.1 8.2 8.3
 vips 7.0 7.1 7.2 7.3 7.4 8.0 8.1 8.2 8.3
 vld 5.5 5.6 7.0 7.1 7.2 7.3 7.4 8.0 8.1 8.2 8.3
 wddx 5.5 5.6 7.0 7.1 7.2 7.3
+wikidiff2 7.1 7.2 7.3 7.4 8.0 8.1 8.2 8.3
 xdebug 5.5 5.6 7.0 7.1 7.2 7.3 7.4 8.0 8.1 8.2 8.3
 xdiff 5.5 5.6 7.0 7.1 7.2 7.3 7.4 8.0 8.1 8.2 8.3
 xhprof 5.5 5.6 7.0 7.1 7.2 7.3 7.4 8.0 8.1 8.2 8.3
diff --git a/install-php-extensions b/install-php-extensions
index 3c68e11..22f4c5f 100755
--- a/install-php-extensions
+++ b/install-php-extensions
@@ -1458,6 +1458,14 @@ buildRequiredPackageLists() {
 			wddx@debian)
 				buildRequiredPackageLists_volatile="$buildRequiredPackageLists_volatile libxml2-dev"
 				;;
+			wikidiff2@alpine)
+				buildRequiredPackageLists_persistent="$buildRequiredPackageLists_persistent libstdc++"
+				buildRequiredPackageLists_volatile="$buildRequiredPackageLists_volatile git"
+				;;
+			wikidiff2@debian)
+				buildRequiredPackageLists_persistent="$buildRequiredPackageLists_persistent libthai0"
+				buildRequiredPackageLists_volatile="$buildRequiredPackageLists_volatile git libthai-dev"
+				;;
 			xdebug@alpine)
 				if test $PHP_MAJMIN_VERSION -ge 800; then
 					buildRequiredPackageLists_volatile="$buildRequiredPackageLists_volatile linux-headers"
@@ -2232,6 +2240,59 @@ installLibMPDec() {
 	cd - >/dev/null
 }
 
+# Check if libdatrie is installed
+#
+# Return:
+#   0 (true)
+#   1 (false)
+isLibDatrieInstalled() {
+	if ! test -f /usr/local/lib/libdatrie.so && ! test -f /usr/lib/libdatrie.so && ! test -f /usr/lib/x86_64*/libdatrie.so; then
+		return 1
+	fi
+	if ! test -f /usr/local/include/datrie/trie.h && ! test -f /usr/include/datrie/trie.h; then
+		return 1
+	fi
+	return 0
+}
+
+# Install libdatrie
+installLibDatrie() {
+	printf 'Installing libdatrie\n'
+	installLibDatrie_src="$(getPackageSource https://github.com/tlwg/libdatrie/releases/download/v0.2.13/libdatrie-0.2.13.tar.xz)"
+	cd -- "$installLibDatrie_src"
+	./configure
+	make -j$(getProcessorCount)
+	make install
+	cd - >/dev/null
+}
+
+# Check if libdatrie is installed
+#
+# Return:
+#   0 (true)
+#   1 (false)
+isLibThaiInstalled() {
+	return 1
+	if ! test -f /usr/local/lib/libthai.so && ! test -f /usr/lib/libthai.so && ! test -f /usr/lib/x86_64*/libthai.so; then
+		return 1
+	fi
+	if ! test -f /usr/local/include/thai/thailib.h && ! test -f /usr/include/thai/thailib.h; then
+		return 1
+	fi
+	return 0
+}
+
+# Install libdatrie
+installLibThai() {
+	printf 'Installing libthai\n'
+	installLibThai_src="$(getPackageSource https://github.com/tlwg/libthai/releases/download/v0.1.29/libthai-0.1.29.tar.xz)"
+	cd -- "$installLibThai_src"
+	./configure
+	make -j$(getProcessorCount)
+	make install
+	cd - >/dev/null
+}
+
 # Install Composer
 installComposer() {
 	installComposer_version="$(getWantedPHPModuleVersion @composer)"
@@ -4053,6 +4114,33 @@ installRemoteModule() {
 				fi
 			fi
 			;;
+		wikidiff2)
+			case "$DISTRO" in
+				alpine)
+					if ! isLibDatrieInstalled; then
+						installLibDatrie
+					fi
+					if ! isLibThaiInstalled; then
+						installLibThai
+					fi
+					;;
+			esac
+			if test -z "$installRemoteModule_version"; then
+				if test $PHP_MAJMIN_VERSION -le 702; then
+					installRemoteModule_version=1.13.0
+				else
+					installRemoteModule_version="$(git -c versionsort.suffix=- ls-remote --tags --refs --quiet --exit-code --sort=version:refname https://github.com/wikimedia/mediawiki-php-wikidiff2.git 'refs/tags/*.*.*' | tail -1 | cut -d/ -f3)"
+				fi
+			fi
+			installRemoteModule_src="$(getPackageSource "https://codeload.github.com/wikimedia/mediawiki-php-wikidiff2/tar.gz/refs/tags/$installRemoteModule_version")"
+			cd -- "$installRemoteModule_src"
+			phpize
+			./configure
+			make -j$(getProcessorCount)
+			make install
+			cd - >/dev/null
+			installRemoteModule_manuallyInstalled=1
+			;;
 		xdebug)
 			if test -z "$installRemoteModule_version"; then
 				if test $PHP_MAJMIN_VERSION -le 500; then
@@ -4507,7 +4595,7 @@ fixLetsEncrypt() {
 					invokeAptGetUpdate
 				fi
 				printf -- '- installing newer ca-certificates package\n'
-				DEBIAN_FRONTEND=noninteractive apt-get install -qqy --no-install-recommends $IPE_APTGET_INSTALLOPTIONS ca-certificates
+				DEBIAN_FRONTEND=noninteractive apt-get install -qqy --no-install-recommends ${IPE_APTGET_INSTALLOPTIONS:-} ca-certificates
 			fi
 			;;
 		*)
diff --git a/scripts/tests/wikidiff2 b/scripts/tests/wikidiff2
new file mode 100755
index 0000000..1c95ecb
--- /dev/null
+++ b/scripts/tests/wikidiff2
@@ -0,0 +1,13 @@
+#!/usr/bin/env php
+<?php
+
+require_once __DIR__ . '/_bootstrap.php';
+
+$diff = wikidiff2_inline_json_diff("a\nb\nc", "a\nd\nc", 1);
+$data = json_decode($diff, true);
+if (!is_array($data)) {
+    fwrite(STDERR, "Unexpected result of wikidiff2_inline_json_diff():\n{$diff}\n");
+    exit(1);
+}
+echo "wikidiff2 works as expected\n";
+exit(0);