diff --git a/Cargo.toml b/Cargo.toml
index 0df83978a..a90bf738c 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -259,6 +259,7 @@ check-cfg = [
     'cfg(linux_kernel)',
     'cfg(linux_like)',
     'cfg(linux_raw)',
+    'cfg(lower_upper_exp_for_non_zero)',
     'cfg(netbsdlike)',
     'cfg(rustc_attrs)',
     'cfg(solarish)',
diff --git a/build.rs b/build.rs
index d2d6541f4..981e82612 100644
--- a/build.rs
+++ b/build.rs
@@ -79,6 +79,11 @@ fn main() {
         use_feature("static_assertions");
     }
 
+    // `LowerExp`/`UpperExp` for `NonZeroI32` etc.
+    if has_lower_upper_exp_for_non_zero() {
+        use_feature("lower_upper_exp_for_non_zero");
+    }
+
     // WASI support can utilize wasi_ext if present.
     if os == "wasi" {
         use_feature_or_nothing("wasi_ext");
@@ -188,6 +193,12 @@ fn use_thumb_mode() -> bool {
     !can_compile("pub unsafe fn f() { core::arch::asm!(\"udf #16\", in(\"r7\") 0); }")
 }
 
+fn has_lower_upper_exp_for_non_zero() -> bool {
+    // LowerExp/UpperExp for NonZero* were added in Rust 1.84.
+    // <https://doc.rust-lang.org/stable/std/fmt/trait.LowerExp.html#impl-LowerExp-for-NonZero%3CT%3E>
+    can_compile("fn a(x: &core::num::NonZeroI32, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result { core::fmt::LowerExp::fmt(x, f) }")
+}
+
 fn use_feature_or_nothing(feature: &str) {
     if has_feature(feature) {
         use_feature(feature);
diff --git a/src/pid.rs b/src/pid.rs
index 0c23927fb..fc0dc9e68 100644
--- a/src/pid.rs
+++ b/src/pid.rs
@@ -127,11 +127,13 @@ impl fmt::UpperHex for Pid {
         self.0.fmt(f)
     }
 }
+#[cfg(lower_upper_exp_for_non_zero)]
 impl fmt::LowerExp for Pid {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         self.0.fmt(f)
     }
 }
+#[cfg(lower_upper_exp_for_non_zero)]
 impl fmt::UpperExp for Pid {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         self.0.fmt(f)