diff --git a/tslang/include/TypeScript/MLIRLogic/MLIRGenStore.h b/tslang/include/TypeScript/MLIRLogic/MLIRGenStore.h
index 6b6c91222..a6cbabe92 100644
--- a/tslang/include/TypeScript/MLIRLogic/MLIRGenStore.h
+++ b/tslang/include/TypeScript/MLIRLogic/MLIRGenStore.h
@@ -779,6 +779,8 @@ struct ClassInfo
     bool hasRTTI;
     ProcessingStages processingAtEvaluation;
     ProcessingStages processing;
+    // the module `processing` was reached in: a discovery module is thrown away with what it holds
+    mlir::Operation *processingModule = nullptr;
 
     ClassInfo()
         : isDeclaration(false), hasNew(false), hasConstructor(false), constructorAccessLevel(mlir_ts::AccessLevel::Public), hasInitializers(false), hasStaticConstructor(false),
diff --git a/tslang/lib/TypeScript/MLIRGenClasses.cpp b/tslang/lib/TypeScript/MLIRGenClasses.cpp
index 653eff3d0..559410bb1 100644
--- a/tslang/lib/TypeScript/MLIRGenClasses.cpp
+++ b/tslang/lib/TypeScript/MLIRGenClasses.cpp
@@ -115,12 +115,21 @@ namespace mlirgen
 
             // do not process specialized class second time;
             // TODO: investigate why classType is provided already for class
-            if (testProcessingState(newClassPtr, ProcessingStages::Processing, genContext))
+            // Not across modules, though: an import met during discovery is generated in full, but
+            // into the discovery module, which is erased. The members of a specialization made there
+            // are gone, and the module that uses it has to have its own.
+            if (testProcessingState(newClassPtr, ProcessingStages::Processing, genContext)
+                && (genContext.allowPartialResolve || newClassPtr->processingModule == theModule.getOperation()))
             {
                 return {mlir::success(), newClassPtr->classType.getName().getValue()};
             }
         }
 
+        if (!genContext.allowPartialResolve)
+        {
+            newClassPtr->processingModule = theModule.getOperation();
+        }
+
         setProcessingState(newClassPtr, ProcessingStages::Processing, genContext);
 
         auto location = loc(classDeclarationAST);
diff --git a/tslang/lib/TypeScript/MLIRGenGenerics.cpp b/tslang/lib/TypeScript/MLIRGenGenerics.cpp
index 5b7dfd0ed..63dbf37e2 100644
--- a/tslang/lib/TypeScript/MLIRGenGenerics.cpp
+++ b/tslang/lib/TypeScript/MLIRGenGenerics.cpp
@@ -1141,6 +1141,10 @@ namespace mlirgen
                        << " name: " << typeAlias.getKey() << " type: " << typeAlias.getValue();
                        llvm::dbgs() << "\n";);
 
+            // generated in full even inside an imported file; see the overload below
+            MLIRValueGuard<bool> declarationModeGuard(declarationMode);
+            declarationMode = false;
+
             // create new instance of interface with TypeArguments
             if (mlir::failed(std::get<0>(mlirGen(genericClassInfo->classDeclaration, genericTypeGenContext))))
             {
@@ -1217,6 +1221,13 @@ namespace mlirgen
                 // llvm_unreachable(s.c_str());
             }
 
+            // A specialization belongs to every module that uses it (its members are linkonce_odr),
+            // so it is generated in full even while an imported file is only being declared: the
+            // module keeps this copy for its own uses too, and must not depend on the imported
+            // module's object happening to keep the members it needs.
+            MLIRValueGuard<bool> declarationModeGuard(declarationMode);
+            declarationMode = false;
+
             auto res = std::get<0>(mlirGen(genericClassInfo->classDeclaration, genericTypeGenContext));
             count--;
 
diff --git a/tslang/test/tester/CMakeLists.txt b/tslang/test/tester/CMakeLists.txt
index 630d58d79..9710f38bc 100644
--- a/tslang/test/tester/CMakeLists.txt
+++ b/tslang/test/tester/CMakeLists.txt
@@ -2433,6 +2433,12 @@ set(import_bindings_dir "${PROJECT_SOURCE_DIR}/test/tester/import-bindings")
 tslang_add_import_tests(import-bindings-renamed "${import_bindings_dir}" import_renamed names_module)
 tslang_add_import_tests(import-bindings-namespace "${import_bindings_dir}" import_namespace names_module)
 
+# A generic class specialized while its module was imported lost its members (#231).
+set(import_specialization_dir "${PROJECT_SOURCE_DIR}/test/tester/import-specialization")
+# Static linking only: through a -shared library the importer cannot name Box yet ("generic type
+# Box can't be found"), a separate gap.
+tslang_add_test(NAME test-compile-import-specialization COMMAND test-runner "${import_specialization_dir}/import_specialization.ts" "${import_specialization_dir}/box_module.ts")
+
 # The same for a shared library: imported directly and through a source module - see
 # shared-import-reimport.cmake.
 if (WIN32)
diff --git a/tslang/test/tester/import-specialization/box_module.ts b/tslang/test/tester/import-specialization/box_module.ts
new file mode 100644
index 000000000..8094e9f49
--- /dev/null
+++ b/tslang/test/tester/import-specialization/box_module.ts
@@ -0,0 +1,33 @@
+// A module whose class has a field of a generic class specialized on it.
+
+export class Box<T> {
+    items: T[] = [];
+
+    [index: int]: T;
+
+    get(index: int): T {
+        return this.items[index];
+    }
+
+    set(index: int, value: T) {
+        this.items[index] = value;
+    }
+
+    add(v: T) {
+        this.items.push(v);
+    }
+
+    get length() {
+        return this.items.length;
+    }
+}
+
+export class Tree {
+    name: string;
+    children: Box<Tree>;
+
+    constructor(name: string) {
+        this.name = name;
+        this.children = new Box<Tree>();
+    }
+}
diff --git a/tslang/test/tester/import-specialization/import_specialization.ts b/tslang/test/tester/import-specialization/import_specialization.ts
new file mode 100644
index 000000000..54c70007f
--- /dev/null
+++ b/tslang/test/tester/import-specialization/import_specialization.ts
@@ -0,0 +1,34 @@
+// Box<Tree> is first specialized while its module is imported, during this file's discovery pass.
+// Its members went into the discovery module, which is thrown away, and the specialization was
+// then taken as done: calls to them here failed to lower ("failed to legalize operation
+// 'ts.SymbolCallInternal'"), found in the BrowserLib sources attached to #231.
+
+import { Tree } from "./box_module";
+
+function find(n: Tree, name: string): Tree | null {
+    if (n.name == name) {
+        return n;
+    }
+
+    for (let i = 0; i < n.children.length; i++) {
+        const found = find(n.children[i], name);
+        if (found !== null) {
+            return found;
+        }
+    }
+
+    return null;
+}
+
+function main() {
+    const root = new Tree("root");
+    const a = new Tree("a");
+    root.children.add(a);
+    a.children.add(new Tree("b"));
+
+    assert(find(root, "b") !== null);
+    assert(find(root, "z") === null);
+    assert(root.children[0].name == "a");
+
+    print("done.");
+}