diff --git a/lang/src/son.rs b/lang/src/son.rs
index b72539dc..1464b48f 100644
--- a/lang/src/son.rs
+++ b/lang/src/son.rs
@@ -27,6 +27,7 @@ use {
     },
     hashbrown::hash_map,
     hbbytecode::DisasmError,
+    std::backtrace,
 };
 
 const VOID: Nid = 0;
@@ -443,6 +444,7 @@ impl Nodes {
 
     fn bind(&mut self, from: Nid, to: Nid) {
         debug_assert_ne!(to, 0);
+        debug_assert_ne!(self[to].kind, Kind::Phi);
         self[from].outputs.push(to);
         self[to].inputs.push(from);
     }
@@ -714,6 +716,12 @@ impl Nodes {
             return false;
         }
 
+        if self[target].kind == (Kind::BinOp { op: TokenKind::Add })
+            && self[target].ty == ty::Id::U8
+        {
+            log::info!("{}", std::backtrace::Backtrace::capture());
+        }
+
         for i in 0..self[target].inputs.len() {
             let inp = self[target].inputs[i];
             let index = self[inp].outputs.iter().position(|&p| p == target).unwrap();
@@ -1503,7 +1511,8 @@ impl Nodes {
             Kind::Load => write!(out, "load:      "),
             Kind::Stre => write!(out, "stre:      "),
             Kind::Mem => write!(out, " mem:      "),
-            Kind::Loops => write!(out, " loops:      "),
+            Kind::Loops => write!(out, "loops:      "),
+            Kind::Join => write!(out, "join:     "),
         }?;
 
         if self[node].kind != Kind::Loop && self[node].kind != Kind::Region {
@@ -1850,6 +1859,8 @@ pub enum Kind {
     Load,
     // [ctrl, value, memory]
     Stre,
+    // [ctrl, a, b]
+    Join,
 }
 
 impl Kind {
@@ -2474,11 +2485,15 @@ impl<'a> Codegen<'a> {
             );
             let base_class = self.ci.scope.aclasses[0].last_store.get();
             let last_store = self.ci.scope.aclasses[value_index].last_store.get();
-            if base_class != MEM && last_store != MEM {
-                self.ci.nodes.bind(base_class, last_store);
-            }
-            if last_store != MEM {
-                self.ci.scope.aclasses[0].last_store.set(last_store, &mut self.ci.nodes);
+            match [base_class, last_store] {
+                [_, MEM] => {}
+                [MEM, a] => {
+                    self.ci.scope.aclasses[0].last_store.set(a, &mut self.ci.nodes);
+                }
+                [a, b] => {
+                    let a = self.ci.nodes.new_node_nop(ty::Id::VOID, Kind::Join, [0, a, b]);
+                    self.ci.scope.aclasses[0].last_store.set(a, &mut self.ci.nodes);
+                }
             }
         }
 
@@ -3649,7 +3664,11 @@ impl<'a> Codegen<'a> {
                         dest_class.last_store.set(scope_class.last_store.get(), &mut self.ci.nodes);
                     }
 
-                    debug_assert!(!self.ci.nodes[dest_class.last_store.get()].is_lazy_phi(node));
+                    debug_assert!(
+                        !self.ci.nodes[dest_class.last_store.get()].is_lazy_phi(node),
+                        "{:?}",
+                        self.ci.nodes[dest_class.last_store.get()]
+                    );
                 }
 
                 scope.clear(&mut self.ci.nodes);
diff --git a/lang/src/son/hbvm/my_regalloc.rs b/lang/src/son/hbvm/my_regalloc.rs
index 9a38e1c9..fe8d87cc 100644
--- a/lang/src/son/hbvm/my_regalloc.rs
+++ b/lang/src/son/hbvm/my_regalloc.rs
@@ -468,6 +468,7 @@ impl HbvmBackend {
                     | Kind::Then
                     | Kind::Else
                     | Kind::Phi
+                    | Kind::Join
                     | Kind::Assert { .. }) => unreachable!("{e:?}"),
                 }
             }
@@ -731,7 +732,7 @@ impl<'a> Function<'a> {
             | Kind::Load { .. }
             | Kind::Stre
             | Kind::Stck => self.add_instr(nid),
-            Kind::End | Kind::Phi | Kind::Arg | Kind::Mem | Kind::Loops => {}
+            Kind::End | Kind::Phi | Kind::Arg | Kind::Mem | Kind::Loops | Kind::Join => {}
             Kind::Assert { .. } => unreachable!(),
         }
     }
diff --git a/lang/src/son/hbvm/their_regalloc.rs b/lang/src/son/hbvm/their_regalloc.rs
index d0f1ca85..a4e36f03 100644
--- a/lang/src/son/hbvm/their_regalloc.rs
+++ b/lang/src/son/hbvm/their_regalloc.rs
@@ -431,7 +431,8 @@ impl HbvmBackend {
                     | Kind::Then
                     | Kind::Else
                     | Kind::Phi
-                    | Kind::Arg => unreachable!(),
+                    | Kind::Arg
+                    | Kind::Join => unreachable!(),
                 }
             }
         }
@@ -835,7 +836,7 @@ impl<'a> Function<'a> {
                 self.add_instr(nid, ops);
             }
             Kind::Assert { .. } => unreachable!(),
-            Kind::End | Kind::Phi | Kind::Arg | Kind::Mem | Kind::Loops => {}
+            Kind::End | Kind::Phi | Kind::Arg | Kind::Mem | Kind::Loops | Kind::Join => {}
             Kind::Load { .. } => {
                 let mut region = node.inputs[1];
                 if self.nodes[region].kind == (Kind::BinOp { op: TokenKind::Add })