diff --git a/src/fillers.rs b/src/fillers.rs
new file mode 100644
index 0000000..2d2b4c6
--- /dev/null
+++ b/src/fillers.rs
@@ -0,0 +1,69 @@
+use num::traits::Num;
+
+use super::error::DspError;
+
+pub struct ConstFiller<'a, NumType>
+where
+    NumType: Num + Copy,
+{
+    value: NumType,
+    iterator: Box<dyn Iterator<Item = Result<NumType, DspError>> + 'a>,
+}
+
+impl<'a, NumType> ConstFiller<'a, NumType>
+where
+    NumType: Num + Copy,
+{
+    pub fn from<I>(iterator: I, value: NumType) -> ConstFiller<'a, NumType>
+    where
+        I: Iterator<Item = Result<NumType, DspError>> + 'a,
+    {
+        ConstFiller {
+            value: value,
+            iterator: Box::new(iterator),
+        }
+    }
+}
+
+impl<'a, NumType> Iterator for ConstFiller<'a, NumType>
+where
+    NumType: Num + Copy,
+{
+    type Item = Result<NumType, DspError>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        match self.iterator.next() {
+            Some(Ok(x)) => Some(Ok(x)),
+            Some(Err(DspError::WouldBlock)) => Some(Ok(self.value)),
+            Some(Err(e)) => Some(Err(e)),
+            None => None,
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn const_filler_test() {
+        let test = vec![
+            Ok(4_f32),
+            Err(DspError::WouldBlock),
+            Ok(5_f32),
+            Err(DspError::WouldBlock),
+            Ok(6_f32),
+            Ok(7_f32),
+        ];
+
+        let mut filler = ConstFiller::from(test.into_iter(), 23_f32);
+
+        assert_eq!(filler.next(), Some(Ok(4_f32)));
+        assert_eq!(filler.next(), Some(Ok(23_f32)));
+        assert_eq!(filler.next(), Some(Ok(5_f32)));
+        assert_eq!(filler.next(), Some(Ok(23_f32)));
+        assert_eq!(filler.next(), Some(Ok(6_f32)));
+        assert_eq!(filler.next(), Some(Ok(7_f32)));
+        assert_eq!(filler.next(), None);
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index 3deb783..dca9409 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,5 +1,6 @@
 mod amdemod;
 mod error;
+mod fillers;
 mod firfilter;
 mod multiply;
 mod resamplers;