diff --git a/beacon_chain/validation/src/attestation_validation.rs b/beacon_chain/validation/src/attestation_validation.rs
index bb458ebc72..057703013f 100644
--- a/beacon_chain/validation/src/attestation_validation.rs
+++ b/beacon_chain/validation/src/attestation_validation.rs
@@ -29,6 +29,7 @@ use super::signature_verification::{
 #[derive(Debug,PartialEq)]
 pub enum AttestationValidationError {
     ParentSlotTooHigh,
+    ParentSlotTooLow,
     BlockSlotTooHigh,
     BlockSlotTooLow,
     JustifiedSlotIncorrect,
@@ -94,11 +95,11 @@ impl<T> AttestationValidationContext<T>
 
         /*
          * The slot of this attestation must not be more than cycle_length + 1 distance
-         * from the block that contained it.
+         * from the parent_slot of block that contained it.
          */
-        if a.slot < self.block_slot
+        if a.slot < self.parent_block_slot
             .saturating_sub(u64::from(self.cycle_length).saturating_add(1)) {
-            return Err(AttestationValidationError::BlockSlotTooLow);
+            return Err(AttestationValidationError::ParentSlotTooLow);
         }
 
         /*
diff --git a/beacon_chain/validation/tests/attestation_validation/tests.rs b/beacon_chain/validation/tests/attestation_validation/tests.rs
index f09da33136..013750af3c 100644
--- a/beacon_chain/validation/tests/attestation_validation/tests.rs
+++ b/beacon_chain/validation/tests/attestation_validation/tests.rs
@@ -42,6 +42,15 @@ fn test_attestation_validation_invalid_parent_slot_too_high() {
     assert_eq!(result, Err(AttestationValidationError::ParentSlotTooHigh));
 }
 
+#[test]
+fn test_attestation_validation_invalid_parent_slot_too_low() {
+    let mut rig = generic_rig();
+
+    rig.attestation.slot = rig.context.parent_block_slot - u64::from(rig.context.cycle_length) - 2;
+    let result = rig.context.validate_attestation(&rig.attestation);
+    assert_eq!(result, Err(AttestationValidationError::ParentSlotTooLow));
+}
+
 #[test]
 fn test_attestation_validation_invalid_block_slot_too_high() {
     let mut rig = generic_rig();
@@ -56,7 +65,7 @@ fn test_attestation_validation_invalid_block_slot_too_high() {
 fn test_attestation_validation_invalid_block_slot_too_low() {
     let mut rig = generic_rig();
 
-    rig.attestation.slot = rig.context.block_slot - u64::from(rig.context.cycle_length) - 2;
+    rig.context.block_slot = rig.context.block_slot + u64::from(rig.context.cycle_length);
     let result = rig.context.validate_attestation(&rig.attestation);
     assert_eq!(result, Err(AttestationValidationError::BlockSlotTooLow));
 }