diff --git a/examples/escrow_with_delay.simf b/examples/escrow_with_delay.simf
index 67dd3d3e..8a11a54a 100644
--- a/examples/escrow_with_delay.simf
+++ b/examples/escrow_with_delay.simf
@@ -51,7 +51,7 @@ fn timeout_spend(sender_sig: Signature) {
     let sender_pk: Pubkey = 0x79be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798; // 1 * G
     checksig(sender_pk, sender_sig);
     let timeout: Distance = 1000;
-    jet::check_lock_distance(timeout);
+    jet::broken_do_not_use_check_lock_distance(timeout);
 }
 
 fn main() {
diff --git a/src/ast.rs b/src/ast.rs
index 6cda4851..1701dece 100644
--- a/src/ast.rs
+++ b/src/ast.rs
@@ -6,7 +6,7 @@ use std::sync::Arc;
 
 use either::Either;
 use miniscript::iter::{Tree, TreeLike};
-use simplicity::jet::Elements;
+use simplicity::jet::{Elements, Jet};
 
 use crate::debug::{CallTracker, DebugSymbols, TrackedCallName};
 use crate::error::{Error, RichError, Span, WithSpan};
@@ -1294,7 +1294,14 @@ impl AbstractSyntaxTree for CallName {
                 Ok(Elements::CheckSigVerify | Elements::Verify) | Err(_) => {
                     Err(Error::JetDoesNotExist(name.clone())).with_span(from)
                 }
-                Ok(jet) => Ok(Self::Jet(jet)),
+                Ok(jet) => {
+                    // TODO: in future, we will want this to be a warning, but that would mean that
+                    // you need to change all methods to return warnings.
+                    if jet.is_deprecated() {
+                        return Err(Error::JetIsDeprecated(name.clone())).with_span(from);
+                    }
+                    Ok(Self::Jet(jet))
+                }
             },
             parse::CallName::UnwrapLeft(right_ty) => scope
                 .resolve(right_ty)
diff --git a/src/error.rs b/src/error.rs
index c06cc90b..b283e4ea 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -437,6 +437,7 @@ pub enum Error {
     ModuleRedefined(ModuleName),
     ArgumentMissing(WitnessName),
     ArgumentTypeMismatch(WitnessName, ResolvedType, ResolvedType),
+    JetIsDeprecated(JetName),
 }
 
 #[rustfmt::skip]
@@ -490,6 +491,10 @@ impl fmt::Display for Error {
                 f,
                 "Jet `{name}` does not exist"
             ),
+            Error::JetIsDeprecated(name) => write!(
+                f, 
+                "Jet `{name}` has been deprecrated."
+            ),
             Error::InvalidCast(source, target) => write!(
                 f,
                 "Cannot cast values of type `{source}` as values of type `{target}`"
diff --git a/src/jet.rs b/src/jet.rs
index cf6a1fcb..724b73a2 100644
--- a/src/jet.rs
+++ b/src/jet.rs
@@ -450,12 +450,12 @@ pub fn source_type(jet: Elements) -> Vec<AliasedType> {
          * Time locks
          */
         Elements::CheckLockTime => vec![Time.into()],
-        Elements::CheckLockDistance => vec![Distance.into()],
-        Elements::CheckLockDuration => vec![Duration.into()],
+        Elements::BrokenDoNotUseCheckLockDistance => vec![Distance.into()],
+        Elements::BrokenDoNotUseCheckLockDuration => vec![Duration.into()],
         Elements::CheckLockHeight => vec![Height.into()],
         Elements::TxLockTime
-        | Elements::TxLockDistance
-        | Elements::TxLockDuration
+        | Elements::BrokenDoNotUseTxLockDistance
+        | Elements::BrokenDoNotUseTxLockDuration
         | Elements::TxLockHeight
         | Elements::TxIsFinal => vec![],
         /*
@@ -956,13 +956,13 @@ pub fn target_type(jet: Elements) -> AliasedType {
          * Time locks
          */
         Elements::CheckLockTime
-        | Elements::CheckLockDistance
-        | Elements::CheckLockDuration
+        | Elements::BrokenDoNotUseCheckLockDistance
+        | Elements::BrokenDoNotUseCheckLockDuration
         | Elements::CheckLockHeight => AliasedType::unit(),
         Elements::TxIsFinal => bool(),
         Elements::TxLockTime => Time.into(),
-        Elements::TxLockDistance => Distance.into(),
-        Elements::TxLockDuration => Duration.into(),
+        Elements::BrokenDoNotUseTxLockDistance => Distance.into(),
+        Elements::BrokenDoNotUseTxLockDuration => Duration.into(),
         Elements::TxLockHeight => Height.into(),
         /*
          * Issuance