diff --git a/implementations/rust/preserves-schema/src/compiler/context.rs b/implementations/rust/preserves-schema/src/compiler/context.rs
index 9da8117..97337c7 100644
--- a/implementations/rust/preserves-schema/src/compiler/context.rs
+++ b/implementations/rust/preserves-schema/src/compiler/context.rs
@@ -73,8 +73,8 @@ impl<'b> BundleContext<'b> {
         }
     }
 
-    pub fn type_for_name(&self, r: &Ref) -> &types::TDefinition {
-        self.types.get(r).unwrap_or_else(|| panic!("{:?} not found", r))
+    pub fn type_for_name(&self, r: &Ref) -> Option<&types::TDefinition> {
+        self.types.get(r)
     }
 
     pub fn define_literal(&mut self, v: &IOValue) -> String {
@@ -153,7 +153,7 @@ impl<'m, 'b> ModuleContext<'m, 'b> {
             Some(s) =>
                 item(name![s.to_owned(), r.name.to_owned()])
         };
-        if with_generic_args && self.type_for_name(r).has_embedded(self) {
+        if with_generic_args && self.ref_has_embedded(r) {
             item(seq![base, anglebrackets!["_Any"]])
         } else {
             base
@@ -172,10 +172,17 @@ impl<'m, 'b> ModuleContext<'m, 'b> {
         }
     }
 
-    pub fn type_for_name(&self, r: &Ref) -> &types::TDefinition {
+    pub fn type_for_name(&self, r: &Ref) -> Option<&types::TDefinition> {
         self.bundle.type_for_name(&self.qualify(r))
     }
 
+    pub fn ref_has_embedded(&self, r: &Ref) -> bool {
+        match self.type_for_name(r) {
+            Some(ty) => ty.has_embedded(self),
+            None => false, // TODO: should this be configurable?
+        }
+    }
+
     pub fn literals_generic_decls(&self) -> Item {
         item(anglebrackets!["_Any: preserves::value::NestedValue"])
     }
diff --git a/implementations/rust/preserves-schema/src/compiler/types.rs b/implementations/rust/preserves-schema/src/compiler/types.rs
index 4171282..ce4f70b 100644
--- a/implementations/rust/preserves-schema/src/compiler/types.rs
+++ b/implementations/rust/preserves-schema/src/compiler/types.rs
@@ -214,7 +214,7 @@ impl TField {
                     false
                 } else {
                     seen.insert(r.clone());
-                    ctxt.type_for_name(&r)._has_embedded(ctxt, seen)
+                    ctxt.type_for_name(&r).map(|ty| ty._has_embedded(ctxt, seen)).unwrap_or(false)
                 }
             }
             TField::Base(_) => false,