diff --git a/hugr-core/Cargo.toml b/hugr-core/Cargo.toml
index 477f8f499..274c21837 100644
--- a/hugr-core/Cargo.toml
+++ b/hugr-core/Cargo.toml
@@ -20,7 +20,6 @@ workspace = true
 extension_inference = []
 declarative = ["serde_yaml"]
 model_unstable = ["hugr-model"]
-default = ["model_unstable"]
 
 [[test]]
 name = "model"
diff --git a/hugr-core/src/export.rs b/hugr-core/src/export.rs
index 966f3c680..55d586b7b 100644
--- a/hugr-core/src/export.rs
+++ b/hugr-core/src/export.rs
@@ -269,7 +269,6 @@ impl<'a> Context<'a> {
                 let decl = this.bump.alloc(model::AliasDecl {
                     name: &alias.name,
                     params: &[],
-                    constraints: &[],
                     r#type,
                 });
                 model::Operation::DeclareAlias { decl }
@@ -282,7 +281,6 @@ impl<'a> Context<'a> {
                 let decl = this.bump.alloc(model::AliasDecl {
                     name: &alias.name,
                     params: &[],
-                    constraints: &[],
                     r#type,
                 });
                 model::Operation::DefineAlias { decl, value }
diff --git a/hugr-model/capnp/hugr-v0.capnp b/hugr-model/capnp/hugr-v0.capnp
index 19612bf53..94341beba 100644
--- a/hugr-model/capnp/hugr-v0.capnp
+++ b/hugr-model/capnp/hugr-v0.capnp
@@ -70,16 +70,14 @@ struct Operation {
     struct AliasDefn {
         name @0 :Text;
         params @1 :List(Param);
-        constraints @2 :List(TermId);
-        type @3 :TermId;
-        value @4 :TermId;
+        type @2 :TermId;
+        value @3 :TermId;
     }
 
     struct AliasDecl {
         name @0 :Text;
         params @1 :List(Param);
-        constraints @2 :List(TermId);
-        type @3 :TermId;
+        type @2 :TermId;
     }
 
     struct ConstructorDecl {
diff --git a/hugr-model/src/v0/binary/read.rs b/hugr-model/src/v0/binary/read.rs
index e352aba93..5381a7dc8 100644
--- a/hugr-model/src/v0/binary/read.rs
+++ b/hugr-model/src/v0/binary/read.rs
@@ -168,13 +168,11 @@ fn read_operation<'a>(
             let reader = reader?;
             let name = bump.alloc_str(reader.get_name()?.to_str()?);
             let params = read_list!(bump, reader, get_params, read_param);
-            let constraints = read_scalar_list!(bump, reader, get_constraints, model::TermId);
             let r#type = model::TermId(reader.get_type());
             let value = model::TermId(reader.get_value());
             let decl = bump.alloc(model::AliasDecl {
                 name,
                 params,
-                constraints,
                 r#type,
             });
             model::Operation::DefineAlias { decl, value }
@@ -183,12 +181,10 @@ fn read_operation<'a>(
             let reader = reader?;
             let name = bump.alloc_str(reader.get_name()?.to_str()?);
             let params = read_list!(bump, reader, get_params, read_param);
-            let constraints = read_scalar_list!(bump, reader, get_constraints, model::TermId);
             let r#type = model::TermId(reader.get_type());
             let decl = bump.alloc(model::AliasDecl {
                 name,
                 params,
-                constraints,
                 r#type,
             });
             model::Operation::DeclareAlias { decl }
diff --git a/hugr-model/src/v0/binary/write.rs b/hugr-model/src/v0/binary/write.rs
index e6ac64201..f3a0a14d2 100644
--- a/hugr-model/src/v0/binary/write.rs
+++ b/hugr-model/src/v0/binary/write.rs
@@ -75,7 +75,6 @@ fn write_operation(mut builder: hugr_capnp::operation::Builder, operation: &mode
             let mut builder = builder.init_alias_defn();
             builder.set_name(decl.name);
             write_list!(builder, init_params, write_param, decl.params);
-            let _ = builder.set_constraints(model::TermId::unwrap_slice(decl.constraints));
             builder.set_type(decl.r#type.0);
             builder.set_value(value.0);
         }
@@ -83,7 +82,6 @@ fn write_operation(mut builder: hugr_capnp::operation::Builder, operation: &mode
             let mut builder = builder.init_alias_decl();
             builder.set_name(decl.name);
             write_list!(builder, init_params, write_param, decl.params);
-            let _ = builder.set_constraints(model::TermId::unwrap_slice(decl.constraints));
             builder.set_type(decl.r#type.0);
         }
 
diff --git a/hugr-model/src/v0/mod.rs b/hugr-model/src/v0/mod.rs
index 0a5b4c169..16c7cb6c6 100644
--- a/hugr-model/src/v0/mod.rs
+++ b/hugr-model/src/v0/mod.rs
@@ -410,8 +410,6 @@ pub struct AliasDecl<'a> {
     pub name: &'a str,
     /// The static parameters of the alias.
     pub params: &'a [Param<'a>],
-    /// The constraints on the static parameters.
-    pub constraints: &'a [TermId],
     /// The type of the alias.
     pub r#type: TermId,
 }
diff --git a/hugr-model/src/v0/text/hugr.pest b/hugr-model/src/v0/text/hugr.pest
index 4c3bd169e..d05e3d774 100644
--- a/hugr-model/src/v0/text/hugr.pest
+++ b/hugr-model/src/v0/text/hugr.pest
@@ -57,7 +57,7 @@ node_custom            = { "(" ~ (term_apply | term_apply_full) ~ port_lists? ~
 
 signature        = { "(" ~ "signature" ~ term ~ ")" }
 func_header      = { symbol ~ param* ~ where_clause* ~ term ~ term ~ term }
-alias_header     = { symbol ~ param* ~ where_clause* ~ term }
+alias_header     = { symbol ~ param* ~ term }
 ctr_header       = { symbol ~ param* ~ where_clause* ~ term }
 operation_header = { symbol ~ param* ~ where_clause* ~ term }
 
diff --git a/hugr-model/src/v0/text/parse.rs b/hugr-model/src/v0/text/parse.rs
index 672edbbe9..370dbeac0 100644
--- a/hugr-model/src/v0/text/parse.rs
+++ b/hugr-model/src/v0/text/parse.rs
@@ -576,13 +576,11 @@ impl<'a> ParseContext<'a> {
         let mut inner = pair.into_inner();
         let name = self.parse_symbol(&mut inner)?;
         let params = self.parse_params(&mut inner)?;
-        let constraints = self.parse_constraints(&mut inner)?;
         let r#type = self.parse_term(inner.next().unwrap())?;
 
         Ok(self.bump.alloc(AliasDecl {
             name,
             params,
-            constraints,
             r#type,
         }))
     }
diff --git a/hugr-model/src/v0/text/print.rs b/hugr-model/src/v0/text/print.rs
index 561d55e70..512f6d1e4 100644
--- a/hugr-model/src/v0/text/print.rs
+++ b/hugr-model/src/v0/text/print.rs
@@ -294,7 +294,6 @@ impl<'p, 'a: 'p> PrintContext<'p, 'a> {
                 });
 
                 this.print_params(decl.params)?;
-                this.print_constraints(decl.constraints)?;
 
                 this.print_term(decl.r#type)?;
                 this.print_term(*value)?;
@@ -308,7 +307,6 @@ impl<'p, 'a: 'p> PrintContext<'p, 'a> {
                 });
 
                 this.print_params(decl.params)?;
-                this.print_constraints(decl.constraints)?;
 
                 this.print_term(decl.r#type)?;
                 this.print_meta(node_data.meta)?;