diff --git a/src/codec/context.rs b/src/codec/context.rs
index 41dcae7..58448b3 100644
--- a/src/codec/context.rs
+++ b/src/codec/context.rs
@@ -125,13 +125,13 @@ impl Context {
 		Parameters::from(self)
 	}
 
-	pub fn time_base(&self) -> Rational {
-		unsafe { Rational::from((*self.as_ptr()).time_base) }
+	pub fn time_base(&self) -> Option<Rational> {
+		unsafe { Rational::from((*self.as_ptr()).time_base).non_zero() }
 	}
 
-	pub fn set_time_base<R: Into<Rational>>(&mut self, value: R) {
+	pub fn set_time_base<R: Into<Rational>>(&mut self, value: Option<R>) {
 		unsafe {
-			(*self.as_mut_ptr()).time_base = value.into().into();
+			(*self.as_mut_ptr()).time_base = value.map(Into::into).unwrap_or(Rational::ZERO).into();
 		}
 	}
 
diff --git a/src/format/chapter/chapter.rs b/src/format/chapter/chapter.rs
index d5f7d56..00f19cd 100644
--- a/src/format/chapter/chapter.rs
+++ b/src/format/chapter/chapter.rs
@@ -26,8 +26,8 @@ impl<'a> Chapter<'a> {
 		unsafe { (*self.as_ptr()).id }
 	}
 
-	pub fn time_base(&self) -> Rational {
-		unsafe { Rational::from((*self.as_ptr()).time_base) }
+	pub fn time_base(&self) -> Option<Rational> {
+		unsafe { Rational::from((*self.as_ptr()).time_base).non_zero() }
 	}
 
 	pub fn start(&self) -> i64 {
diff --git a/src/format/stream/stream.rs b/src/format/stream/stream.rs
index 60bbd5f..b4f9114 100644
--- a/src/format/stream/stream.rs
+++ b/src/format/stream/stream.rs
@@ -53,8 +53,8 @@ impl<'a> Stream<'a> {
 		unsafe { (*self.as_ptr()).index as usize }
 	}
 
-	pub fn time_base(&self) -> Rational {
-		unsafe { Rational::from((*self.as_ptr()).time_base) }
+	pub fn time_base(&self) -> Option<Rational> {
+		unsafe { Rational::from((*self.as_ptr()).time_base).non_zero() }
 	}
 
 	pub fn start_time(&self) -> Option<i64> {
diff --git a/src/format/stream/stream_mut.rs b/src/format/stream/stream_mut.rs
index 077cf64..902df39 100644
--- a/src/format/stream/stream_mut.rs
+++ b/src/format/stream/stream_mut.rs
@@ -26,9 +26,9 @@ impl<'a> StreamMut<'a> {
 }
 
 impl<'a> StreamMut<'a> {
-	pub fn set_time_base<R: Into<Rational>>(&mut self, value: R) {
+	pub fn set_time_base<R: Into<Rational>>(&mut self, value: Option<R>) {
 		unsafe {
-			(*self.as_mut_ptr()).time_base = value.into().into();
+			(*self.as_mut_ptr()).time_base = value.map(Into::into).unwrap_or(Rational::ZERO).into();
 		}
 	}