diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 05a78c7..71f820d 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -19,6 +19,12 @@ jobs:
                 expect_native: 1
                 werror: 1
 
+              - php: '8.1.0'
+                os: 'ubuntu-18.04'
+                expect_native: 1
+                werror: 1
+                arch: i386
+
               - php: '8.0.0'
                 os: 'ubuntu-20.04'
                 expect_native: 1
@@ -42,6 +48,7 @@ jobs:
             MEMORY_CHECK: ${{ matrix.memcheck }}
             WERROR: ${{ matrix.werror }}
             MEMPROF_EXPECT_NATIVE_TRACKING: ${{ matrix.expect_native }}
+            BUILD_ARCH: ${{ matrix.arch || 'amd64' }}
         steps:
             - name: 'Check out repository'
               uses: 'actions/checkout@v2'
@@ -51,7 +58,10 @@ jobs:
             - uses: actions/cache@v2
               with:
                   path: ~/build-cache/php
-                  key: ${{ runner.os }}-${{ matrix.php }}-${{ matrix.memcheck }}
+                  key: ${{ runner.os }}-${{matrix.arch}}-${{ matrix.php }}-${{ matrix.memcheck }}
+
+            - name: 'Setup'
+              run: './ext/.github/workflows/test/setup.sh'
 
             - name: 'Build PHP'
               run: './ext/.github/workflows/test/build-php.sh'
diff --git a/.github/workflows/test/build-extension.sh b/.github/workflows/test/build-extension.sh
index 1159d88..adc4db7 100755
--- a/.github/workflows/test/build-extension.sh
+++ b/.github/workflows/test/build-extension.sh
@@ -9,7 +9,7 @@ echo "Building extension with PHP version:"
 php --version
 
 if which apt-get >/dev/null 2>&1; then
-    sudo apt-get -y install libjudy-dev
+    sudo apt-get -y install libjudy-dev:$BUILD_ARCH
 else
     brew install traildb/judy/judy
 fi
@@ -18,6 +18,12 @@ if [ "$WERROR" = "1" ]; then
     PHP_EXT_CFLAGS="-Wall -Werror -Wno-deprecated-declarations"
 fi
 
+case "$BUILD_ARCH" in
+    i386)
+        PHP_EXT_CFLAGS="$PHP_EXT_CFLAGS -m32"
+        ;;
+esac
+
 cd ext
 phpize
 CFLAGS="$PHP_EXT_CFLAGS" ./configure
diff --git a/.github/workflows/test/build-php.sh b/.github/workflows/test/build-php.sh
index a227384..34e1187 100755
--- a/.github/workflows/test/build-php.sh
+++ b/.github/workflows/test/build-php.sh
@@ -2,11 +2,15 @@
 
 set -ex
 
+if which apt-get >/dev/null 2>&1; then
+    sudo apt-get -y install zlib1g-dev:$BUILD_ARCH
+fi
+
 if [ "$MEMORY_CHECK" = "1" ]; then
     if which apt-get >/dev/null 2>&1; then
-        sudo apt-get -y install valgrind
+        sudo apt-get -y install valgrind:$BUILD_ARCH
     else
-        break install valgrind
+        brew install valgrind
     fi
 fi
 
@@ -36,7 +40,15 @@ if ! [ -f "$HOME/build-cache/php/$PREFIX/bin/php" ]; then
         PHP_BUILD_FLAGS="$PHP_BUILD_FLAGS --with-valgrind"
     fi
 
-    ./configure $PHP_BUILD_FLAGS $PHP_BUILD_EXTRA_FLAGS
+    case "$BUILD_ARCH" in
+        i386)
+            PHP_BUILD_CFLAGS="$PHP_BUILD_CFLAGS -m32"
+            PHP_BUILD_ASFLAGS="$PHP_BUILD_ASFLAGS -m32"
+            PHP_BUILD_FLAGS="$PHP_BUILD_FLAGS --host=$BUILD_ARCH"
+            ;;
+    esac
+
+    ASFLAGS="$PHP_BUILD_ASFLAGS=" CFLAGS="$PHP_BUILD_CFLAGS" ./configure $PHP_BUILD_FLAGS
     make -j $(nproc)
     rm -rf "$HOME/build-cache/php"
     mkdir -p ~/build-cache/php
diff --git a/.github/workflows/test/build-xdebug.sh b/.github/workflows/test/build-xdebug.sh
index cf313e6..4ac04bc 100755
--- a/.github/workflows/test/build-xdebug.sh
+++ b/.github/workflows/test/build-xdebug.sh
@@ -9,7 +9,13 @@ git clone --depth 1 --branch "3.1.2" "https://github.com/xdebug/xdebug.git"
 
 cd xdebug
 
+case "$BUILD_ARCH" in
+    i386)
+        PHP_EXT_CFLAGS="$PHP_EXT_CFLAGS -m32"
+        ;;
+esac
+
 phpize
-./configure
+CFLAGS="$PHP_EXT_CFLAGS" ./configure
 make
 sudo make install
diff --git a/.github/workflows/test/setup.sh b/.github/workflows/test/setup.sh
new file mode 100755
index 0000000..5b71de0
--- /dev/null
+++ b/.github/workflows/test/setup.sh
@@ -0,0 +1,12 @@
+#!/bin/sh
+
+set -ex
+
+case "$BUILD_ARCH" in
+    i386)
+        echo "Setup $BUILD_ARCH architecture"
+        sudo dpkg --add-architecture "$BUILD_ARCH"
+        sudo apt-get update
+        sudo apt-get install gcc-multilib
+        ;;
+esac