diff --git a/src/libcretonne/layout.rs b/src/libcretonne/layout.rs
index d803858d0a..e0ca2cc3cc 100644
--- a/src/libcretonne/layout.rs
+++ b/src/libcretonne/layout.rs
@@ -67,14 +67,18 @@ impl Layout {
     pub fn append_ebb(&mut self, ebb: Ebb) {
         assert!(!self.is_ebb_inserted(ebb),
                 "Cannot append EBB that is already in the layout");
-        let node = &mut self.ebbs[ebb];
-        assert!(node.first_inst == NO_INST && node.last_inst == NO_INST);
-        node.prev = self.last_ebb.unwrap_or_default();
-        node.next = NO_EBB;
-        self.last_ebb = Some(ebb);
-        if self.first_ebb.is_none() {
+        {
+            let node = &mut self.ebbs[ebb];
+            assert!(node.first_inst == NO_INST && node.last_inst == NO_INST);
+            node.prev = self.last_ebb.unwrap_or_default();
+            node.next = NO_EBB;
+        }
+        if let Some(last) = self.last_ebb {
+            self.ebbs[last].next = ebb;
+        } else {
             self.first_ebb = Some(ebb);
         }
+        self.last_ebb = Some(ebb);
     }
 
     /// Insert `ebb` in the layout before the existing EBB `before`.
@@ -151,13 +155,18 @@ impl Layout {
         assert!(self.is_ebb_inserted(ebb),
                 "Cannot append instructions to EBB not in layout");
         let ebb_node = &mut self.ebbs[ebb];
-        let inst_node = &mut self.insts[inst];
-        inst_node.ebb = ebb;
-        inst_node.prev = ebb_node.last_inst;
-        assert_eq!(inst_node.next, NO_INST);
+        {
+            let inst_node = &mut self.insts[inst];
+            inst_node.ebb = ebb;
+            inst_node.prev = ebb_node.last_inst;
+            assert_eq!(inst_node.next, NO_INST);
+        }
         if ebb_node.first_inst == NO_INST {
             ebb_node.first_inst = inst;
+        } else {
+            self.insts[ebb_node.last_inst].next = inst;
         }
+        ebb_node.last_inst = inst;
     }
 
     /// Insert `inst` before the instruction `before` in the same EBB.
@@ -222,6 +231,44 @@ mod tests {
     use entity_map::EntityRef;
     use entities::{Ebb, Inst};
 
+    #[test]
+    fn append_ebb() {
+        let mut layout = Layout::new();
+        let e0 = Ebb::new(0);
+        let e1 = Ebb::new(1);
+        let e2 = Ebb::new(2);
+
+        {
+            let imm = &layout;
+            assert!(!imm.is_ebb_inserted(e0));
+            assert!(!imm.is_ebb_inserted(e1));
+
+            let v: Vec<Ebb> = layout.ebbs().collect();
+            assert_eq!(v, []);
+        }
+
+        layout.append_ebb(e1);
+        assert!(!layout.is_ebb_inserted(e0));
+        assert!(layout.is_ebb_inserted(e1));
+        assert!(!layout.is_ebb_inserted(e2));
+        let v: Vec<Ebb> = layout.ebbs().collect();
+        assert_eq!(v, [e1]);
+
+        layout.append_ebb(e2);
+        assert!(!layout.is_ebb_inserted(e0));
+        assert!(layout.is_ebb_inserted(e1));
+        assert!(layout.is_ebb_inserted(e2));
+        let v: Vec<Ebb> = layout.ebbs().collect();
+        assert_eq!(v, [e1, e2]);
+
+        layout.append_ebb(e0);
+        assert!(layout.is_ebb_inserted(e0));
+        assert!(layout.is_ebb_inserted(e1));
+        assert!(layout.is_ebb_inserted(e2));
+        let v: Vec<Ebb> = layout.ebbs().collect();
+        assert_eq!(v, [e1, e2, e0]);
+    }
+
     #[test]
     fn insert_ebb() {
         let mut layout = Layout::new();
@@ -260,6 +307,45 @@ mod tests {
         assert_eq!(v, [e2, e0, e1]);
     }
 
+    #[test]
+    fn append_inst() {
+        let mut layout = Layout::new();
+        let e1 = Ebb::new(1);
+
+        layout.append_ebb(e1);
+        let v: Vec<Inst> = layout.ebb_insts(e1).collect();
+        assert_eq!(v, []);
+
+        let i0 = Inst::new(0);
+        let i1 = Inst::new(1);
+        let i2 = Inst::new(2);
+
+        assert_eq!(layout.inst_ebb(i0), None);
+        assert_eq!(layout.inst_ebb(i1), None);
+        assert_eq!(layout.inst_ebb(i2), None);
+
+        layout.append_inst(i1, e1);
+        assert_eq!(layout.inst_ebb(i0), None);
+        assert_eq!(layout.inst_ebb(i1), Some(e1));
+        assert_eq!(layout.inst_ebb(i2), None);
+        let v: Vec<Inst> = layout.ebb_insts(e1).collect();
+        assert_eq!(v, [i1]);
+
+        layout.append_inst(i2, e1);
+        assert_eq!(layout.inst_ebb(i0), None);
+        assert_eq!(layout.inst_ebb(i1), Some(e1));
+        assert_eq!(layout.inst_ebb(i2), Some(e1));
+        let v: Vec<Inst> = layout.ebb_insts(e1).collect();
+        assert_eq!(v, [i1, i2]);
+
+        layout.append_inst(i0, e1);
+        assert_eq!(layout.inst_ebb(i0), Some(e1));
+        assert_eq!(layout.inst_ebb(i1), Some(e1));
+        assert_eq!(layout.inst_ebb(i2), Some(e1));
+        let v: Vec<Inst> = layout.ebb_insts(e1).collect();
+        assert_eq!(v, [i1, i2, i0]);
+    }
+
     #[test]
     fn insert_inst() {
         let mut layout = Layout::new();
@@ -298,4 +384,30 @@ mod tests {
         let v: Vec<Inst> = layout.ebb_insts(e1).collect();
         assert_eq!(v, [i2, i0, i1]);
     }
+
+    #[test]
+    fn multiple_ebbs() {
+        let mut layout = Layout::new();
+
+        let e0 = Ebb::new(0);
+        let e1 = Ebb::new(1);
+
+        layout.append_ebb(e0);
+        layout.append_ebb(e1);
+
+        let i0 = Inst::new(0);
+        let i1 = Inst::new(1);
+        let i2 = Inst::new(2);
+        let i3 = Inst::new(3);
+
+        layout.append_inst(i0, e0);
+        layout.append_inst(i1, e0);
+        layout.append_inst(i2, e1);
+        layout.append_inst(i3, e1);
+
+        let v0: Vec<Inst> = layout.ebb_insts(e0).collect();
+        let v1: Vec<Inst> = layout.ebb_insts(e1).collect();
+        assert_eq!(v0, [i0, i1]);
+        assert_eq!(v1, [i2, i3]);
+    }
 }