diff --git a/src/transform/inline.rs b/src/transform/inline.rs
index ca30899c..54875529 100644
--- a/src/transform/inline.rs
+++ b/src/transform/inline.rs
@@ -43,7 +43,7 @@ impl InlineState {
         // Whether or not the tortoise should take a step
         let mut parity = false;
         while let Tree::Ref { nam } = hare {
-          let net = &book.nets[nam];
+          let Some(net) = &book.nets.get(nam) else { break };
           if net.should_inline() {
             hare = &net.root;
           } else {
diff --git a/tests/transform.rs b/tests/transform.rs
index dac96a3d..dba7a227 100644
--- a/tests/transform.rs
+++ b/tests/transform.rs
@@ -108,7 +108,10 @@ pub fn test_inline() {
     @I = (:0:1)
     @K = (:0:2)
     @1234 = (:1:2 (:3:4))
-    @into = ((@era @num @abab @ref @def @eff @I @K) (@into @1234))
+    @foo = @bar
+    @bar = @baz
+    @baz = @unbound
+    @into = ((@era @num @abab @ref @def @eff @I @K) (@into @1234 @foo @bar @baz @unbound))
   ").unwrap(), @r###"
   @1234 = (:1:2 (:3:4))
 
@@ -118,13 +121,19 @@ pub fn test_inline() {
 
   @abab = (a b a b)
 
+  @bar = @unbound
+
+  @baz = @unbound
+
   @def = @abab
 
   @eff = @abab
 
   @era = *
 
-  @into = ((* #123 @abab @abab @abab @abab (:0:1) (:0:2)) (@into @1234))
+  @foo = @unbound
+
+  @into = ((* #123 @abab @abab @abab @abab (:0:1) (:0:2)) (@into @1234 @unbound @unbound @unbound @unbound))
 
   @num = #123