diff --git a/src/items/mod.rs b/src/items/mod.rs
index 51fe78a..1f56077 100644
--- a/src/items/mod.rs
+++ b/src/items/mod.rs
@@ -303,7 +303,7 @@ fn with_timezone_restore(
     offset: time::Offset,
     at: DateTime<FixedOffset>,
 ) -> Option<DateTime<FixedOffset>> {
-    let offset: FixedOffset = chrono::FixedOffset::from(offset);
+    let offset: FixedOffset = chrono::FixedOffset::try_from(offset).ok()?;
     let copy = at;
     let x = at
         .with_timezone(&offset)
@@ -360,7 +360,9 @@ fn at_date_inner(date: Vec<Item>, mut d: DateTime<FixedOffset>) -> Option<DateTi
                     },
                 ..
             }) => {
-                let offset = offset.map(chrono::FixedOffset::from).unwrap_or(*d.offset());
+                let offset = offset
+                    .and_then(|o| chrono::FixedOffset::try_from(o).ok())
+                    .unwrap_or(*d.offset());
 
                 d = new_date(
                     year.map(|x| x as i32).unwrap_or(d.year()),
@@ -379,7 +381,10 @@ fn at_date_inner(date: Vec<Item>, mut d: DateTime<FixedOffset>) -> Option<DateTi
                 second,
                 offset,
             }) => {
-                let offset = offset.map(chrono::FixedOffset::from).unwrap_or(*d.offset());
+                let offset = offset
+                    .and_then(|o| chrono::FixedOffset::try_from(o).ok())
+                    .unwrap_or(*d.offset());
+
                 d = new_date(
                     d.year(),
                     d.month(),
diff --git a/src/items/time.rs b/src/items/time.rs
index 6177f97..7fa8d3f 100644
--- a/src/items/time.rs
+++ b/src/items/time.rs
@@ -50,6 +50,8 @@ use winnow::{
     ModalResult, Parser,
 };
 
+use crate::ParseDateTimeError;
+
 use super::{dec_uint, relative, s};
 
 #[derive(PartialEq, Debug, Clone, Default)]
@@ -95,22 +97,33 @@ impl Offset {
     }
 }
 
-impl From<Offset> for chrono::FixedOffset {
-    fn from(
+impl TryFrom<Offset> for chrono::FixedOffset {
+    type Error = ParseDateTimeError;
+
+    fn try_from(
         Offset {
             negative,
             hours,
             minutes,
         }: Offset,
-    ) -> Self {
+    ) -> Result<Self, Self::Error> {
         let secs = hours * 3600 + minutes * 60;
 
-        if negative {
-            FixedOffset::west_opt(secs.try_into().expect("secs overflow"))
-                .expect("timezone overflow")
+        let offset = if negative {
+            FixedOffset::west_opt(
+                secs.try_into()
+                    .map_err(|_| ParseDateTimeError::InvalidInput)?,
+            )
+            .ok_or(ParseDateTimeError::InvalidInput)?
         } else {
-            FixedOffset::east_opt(secs.try_into().unwrap()).unwrap()
-        }
+            FixedOffset::east_opt(
+                secs.try_into()
+                    .map_err(|_| ParseDateTimeError::InvalidInput)?,
+            )
+            .ok_or(ParseDateTimeError::InvalidInput)?
+        };
+
+        Ok(offset)
     }
 }
 
diff --git a/src/lib.rs b/src/lib.rs
index 9462a75..3e36bf0 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -266,6 +266,12 @@ mod tests {
                 .and_utc();
             assert_eq!(actual, expected);
         }
+
+        #[test]
+        fn offset_overflow() {
+            assert!(parse_datetime("m+12").is_err());
+            assert!(parse_datetime("24:00").is_err());
+        }
     }
 
     #[cfg(test)]