diff --git a/Cargo.lock b/Cargo.lock
index b40e4038..ea076fc1 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -886,6 +886,7 @@ dependencies = [
  "indexmap 2.1.0",
  "jsonschema",
  "mime",
+ "num-traits",
  "pretty_assertions",
  "regex",
  "rmp-serde",
diff --git a/Cargo.toml b/Cargo.toml
index 1d361228..e713ec95 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -48,7 +48,7 @@ explicit_auto_deref = "allow"
 manual-unwrap-or-default = "allow"
 
 # alloc_instead_of_core = "warn"
-# as_conversions = "warn"
+as_conversions = "warn"
 # arithmetic_side_effects = "warn"
 # Checks for usage of `cloned()` on an `Iterator` or `Option` where `copied()` could be used instead.
 cloned_instead_of_copied = "warn"
diff --git a/serde_with/Cargo.toml b/serde_with/Cargo.toml
index c8427997..9ae8aee2 100644
--- a/serde_with/Cargo.toml
+++ b/serde_with/Cargo.toml
@@ -129,6 +129,7 @@ hashbrown_0_14 = {package = "hashbrown", version = "0.14.0", optional = true, de
 hex = {version = "0.4.3", optional = true, default-features = false}
 indexmap_1 = {package = "indexmap", version = "1.8", optional = true, default-features = false, features = ["serde-1"]}
 indexmap_2 = {package = "indexmap", version = "2.0", optional = true, default-features = false, features = ["serde"]}
+num-traits = { version = "0.2.19", features = ["std"] }
 schemars_0_8 = {package = "schemars", version = "0.8.16", optional = true, default-features = false}
 serde = {version = "1.0.152", default-features = false}
 serde_derive = "1.0.152"
diff --git a/serde_with/src/chrono_0_4.rs b/serde_with/src/chrono_0_4.rs
index df34f2b8..d80009d0 100644
--- a/serde_with/src/chrono_0_4.rs
+++ b/serde_with/src/chrono_0_4.rs
@@ -57,6 +57,7 @@ fn unix_epoch_naive() -> NaiveDateTime {
 #[cfg(feature = "std")]
 pub mod datetime_utc_ts_seconds_from_any {
     use super::*;
+    use num_traits::ToPrimitive as _;
 
     /// Deserialize a Unix timestamp with optional subsecond precision into a `DateTime<Utc>`.
     pub fn deserialize<'de, D>(deserializer: D) -> Result<DateTime<Utc>, D::Error>
@@ -87,20 +88,26 @@ pub mod datetime_utc_ts_seconds_from_any {
             where
                 E: DeError,
             {
-                DateTime::from_timestamp(value as i64, 0).ok_or_else(|| {
-                    DeError::custom(format_args!(
+                i64::try_from(value)
+                    .ok()
+                    .and_then(|value| DateTime::from_timestamp(value, 0))
+                    .ok_or_else(|| {
+                        DeError::custom(format_args!(
                         "a timestamp which can be represented in a DateTime but received '{value}'"
                     ))
-                })
+                    })
             }
 
             fn visit_f64<E>(self, value: f64) -> Result<Self::Value, E>
             where
                 E: DeError,
             {
-                let seconds = value.trunc() as i64;
-                let nsecs = (value.fract() * 1_000_000_000_f64).abs() as u32;
-                DateTime::from_timestamp(seconds, nsecs).ok_or_else(|| {
+                fn f64_to_value(value: f64) -> Option<DateTime<Utc>> {
+                    let seconds = value.trunc().to_i64()?;
+                    let nsecs = (value.fract() * 1_000_000_000_f64).abs().to_u32()?;
+                    DateTime::from_timestamp(seconds, nsecs)
+                }
+                f64_to_value(value).ok_or_else(|| {
                     DeError::custom(format_args!(
                         "a timestamp which can be represented in a DateTime but received '{value}'"
                     ))