diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index c31659b9dd..0dbfe1760e 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -6,7 +6,7 @@ jobs:
     build-mlibc:
         strategy:
             matrix:
-                arch: [x86_64, riscv64, aarch64]
+                arch: [x86_64, riscv64, aarch64, x86]
                 builds: [mlibc, mlibc-static, mlibc-shared, mlibc-ansi-only, mlibc-headers-only]
         name: Build mlibc
         runs-on: ubuntu-22.04
diff --git a/ci/linux-x86.cross-file b/ci/linux-x86.cross-file
new file mode 100644
index 0000000000..edad98556a
--- /dev/null
+++ b/ci/linux-x86.cross-file
@@ -0,0 +1,10 @@
+[binaries]
+c = 'i686-linux-mlibc-gcc'
+cpp = 'i686-linux-mlibc-g++'
+exe_wrapper = 'qemu-i386'
+
+[host_machine]
+system = 'linux'
+cpu_family = 'x86'
+cpu = 'i386'
+endian = 'little'
diff --git a/options/posix/include/unistd.h b/options/posix/include/unistd.h
index 26f407d8f5..4cc750763a 100644
--- a/options/posix/include/unistd.h
+++ b/options/posix/include/unistd.h
@@ -305,7 +305,11 @@ extern int optopt;
 #endif /* !__MLIBC_ABI_ONLY */
 
 // Non-POSIX functions supported by Linux.
-typedef unsigned useconds_t;
+#if UINTPTR_MAX == UINT64_MAX
+typedef __mlibc_uint64 useconds_t;
+#else
+typedef __mlibc_uint32 useconds_t;
+#endif
 
 #ifndef __MLIBC_ABI_ONLY