diff --git a/src/imp/libc/fs/types.rs b/src/imp/libc/fs/types.rs
index fbe8af836..7f9e31240 100644
--- a/src/imp/libc/fs/types.rs
+++ b/src/imp/libc/fs/types.rs
@@ -695,7 +695,11 @@ pub type RawMode = libc::mode_t;
 pub type Dev = libc::dev_t;
 
 /// `__fsword_t`
-#[cfg(all(target_os = "linux", not(target_env = "musl")))]
+#[cfg(all(
+    target_os = "linux",
+    not(target_env = "musl"),
+    not(target_arch = "s390x")
+))]
 pub type FsWord = libc::__fsword_t;
 
 /// `__fsword_t`
@@ -708,10 +712,15 @@ pub type FsWord = u32;
 /// `__fsword_t`
 #[cfg(all(
     any(target_os = "android", all(target_os = "linux", target_env = "musl")),
+    not(target_arch = "s390x"),
     target_pointer_width = "64"
 ))]
 pub type FsWord = u64;
 
+// s390x uses u32 for statfs entries, even though __fsword_t is u64.
+#[cfg(all(target_os = "linux", target_arch = "s390x"))]
+pub type FsWord = u32;
+
 #[cfg(not(target_os = "redox"))]
 pub use libc::{UTIME_NOW, UTIME_OMIT};
 
diff --git a/src/imp/libc/io/types.rs b/src/imp/libc/io/types.rs
index 6c6f03837..1f34224ad 100644
--- a/src/imp/libc/io/types.rs
+++ b/src/imp/libc/io/types.rs
@@ -228,6 +228,8 @@ bitflags! {
             target_os = "netbsd",
             target_os = "openbsd",
             target_os = "redox",
+            // TODO: Enable s390x once <https://github.com/rust-lang/libc/pull/2395> lands.
+            target_arch = "s390x",
         )))]
         const SYNC = libc::MAP_SYNC;
         /// `MAP_UNINITIALIZED`