diff --git a/src/objects-debug.cc b/src/objects-debug.cc
index 2a02c4387e..d4ed349da3 100644
--- a/src/objects-debug.cc
+++ b/src/objects-debug.cc
@@ -199,12 +199,14 @@ void HeapObject::HeapObjectVerify() {
     case JS_SPECIAL_API_OBJECT_TYPE:
     case JS_CONTEXT_EXTENSION_OBJECT_TYPE:
     case WASM_GLOBAL_TYPE:
-    case WASM_INSTANCE_TYPE:
     case WASM_MEMORY_TYPE:
     case WASM_MODULE_TYPE:
     case WASM_TABLE_TYPE:
       JSObject::cast(this)->JSObjectVerify();
       break;
+    case WASM_INSTANCE_TYPE:
+      WasmInstanceObject::cast(this)->WasmInstanceObjectVerify();
+      break;
     case JS_ARGUMENTS_TYPE:
       JSArgumentsObject::cast(this)->JSArgumentsObjectVerify();
       break;
@@ -1581,6 +1583,19 @@ void WasmDebugInfo::WasmDebugInfoVerify() {
   VerifyObjectField(kCWasmEntryMapOffset);
 }
 
+void WasmInstanceObject::WasmInstanceObjectVerify() {
+  JSObjectVerify();
+  CHECK(IsWasmInstanceObject());
+
+  // Just generically check all tagged fields. Don't check the untagged fields,
+  // as some of them might still contain the "undefined" value if the
+  // WasmInstanceObject is not fully set up yet.
+  for (int offset = kHeaderSize; offset < kFirstUntaggedOffset;
+       offset += kPointerSize) {
+    VerifyObjectField(offset);
+  }
+}
+
 void WasmExportedFunctionData::WasmExportedFunctionDataVerify() {
   CHECK(IsWasmExportedFunctionData());
   VerifyObjectField(kWrapperCodeOffset);
diff --git a/src/objects-printer.cc b/src/objects-printer.cc
index 43f30fa419..56efb170ee 100644
--- a/src/objects-printer.cc
+++ b/src/objects-printer.cc
@@ -151,13 +151,16 @@ void HeapObject::HeapObjectPrint(std::ostream& os) {  // NOLINT
     case JS_ASYNC_GENERATOR_OBJECT_TYPE:
     case JS_ARGUMENTS_TYPE:
     case JS_ERROR_TYPE:
+    // TODO(titzer): debug printing for more wasm objects
     case WASM_GLOBAL_TYPE:
-    case WASM_INSTANCE_TYPE:  // TODO(titzer): debug printing for wasm objects
     case WASM_MEMORY_TYPE:
     case WASM_MODULE_TYPE:
     case WASM_TABLE_TYPE:
       JSObject::cast(this)->JSObjectPrint(os);
       break;
+    case WASM_INSTANCE_TYPE:
+      WasmInstanceObject::cast(this)->WasmInstanceObjectPrint(os);
+      break;
     case JS_GENERATOR_OBJECT_TYPE:
       JSGeneratorObject::cast(this)->JSGeneratorObjectPrint(os);
       break;
@@ -1661,6 +1664,43 @@ void WasmDebugInfo::WasmDebugInfoPrint(std::ostream& os) {  // NOLINT
   os << "\n";
 }
 
+void WasmInstanceObject::WasmInstanceObjectPrint(std::ostream& os) {  // NOLINT
+  HeapObject::PrintHeader(os, "WasmInstanceObject");
+  os << "\n - compiled_module: " << Brief(compiled_module());
+  os << "\n - module_object: " << Brief(module_object());
+  os << "\n - exports_object: " << Brief(exports_object());
+  os << "\n - native_context: " << Brief(native_context());
+  os << "\n - memory_object: " << Brief(memory_object());
+  os << "\n - globals_buffer: " << Brief(globals_buffer());
+  os << "\n - imported_mutable_globals_buffers: "
+     << Brief(imported_mutable_globals_buffers());
+  os << "\n - debug_info: " << Brief(debug_info());
+  os << "\n - table_object: " << Brief(table_object());
+  os << "\n - imported_function_instances: "
+     << Brief(imported_function_instances());
+  os << "\n - imported_function_callables: "
+     << Brief(imported_function_callables());
+  os << "\n - indirect_function_table_instances: "
+     << Brief(indirect_function_table_instances());
+  os << "\n - managed_native_allocations: "
+     << Brief(managed_native_allocations());
+  os << "\n - managed_indirect_patcher: " << Brief(managed_indirect_patcher());
+  os << "\n - memory_start: " << static_cast<void*>(memory_start());
+  os << "\n - memory_size: " << memory_size();
+  os << "\n - memory_mask: " << AsHex(memory_mask());
+  os << "\n - imported_function_targets: "
+     << static_cast<void*>(imported_function_targets());
+  os << "\n - globals_start: " << static_cast<void*>(globals_start());
+  os << "\n - imported_mutable_globals: "
+     << static_cast<void*>(imported_mutable_globals());
+  os << "\n - indirect_function_table_size: " << indirect_function_table_size();
+  os << "\n - indirect_function_table_sig_ids: "
+     << static_cast<void*>(indirect_function_table_sig_ids());
+  os << "\n - indirect_function_table_targets: "
+     << static_cast<void*>(indirect_function_table_targets());
+  os << "\n";
+}
+
 void WasmExportedFunctionData::WasmExportedFunctionDataPrint(
     std::ostream& os) {  // NOLINT
   HeapObject::PrintHeader(os, "WasmExportedFunctionData");
diff --git a/src/wasm/wasm-objects-inl.h b/src/wasm/wasm-objects-inl.h
index 7628ec2ae0..34b08666f9 100644
--- a/src/wasm/wasm-objects-inl.h
+++ b/src/wasm/wasm-objects-inl.h
@@ -137,10 +137,10 @@ ACCESSORS(WasmInstanceObject, exports_object, JSObject, kExportsObjectOffset)
 ACCESSORS(WasmInstanceObject, native_context, Context, kNativeContextOffset)
 OPTIONAL_ACCESSORS(WasmInstanceObject, memory_object, WasmMemoryObject,
                    kMemoryObjectOffset)
-ACCESSORS(WasmInstanceObject, globals_buffer, JSArrayBuffer,
-          kGlobalsBufferOffset)
-ACCESSORS(WasmInstanceObject, imported_mutable_globals_buffers, FixedArray,
-          kImportedMutableGlobalsBuffersOffset)
+OPTIONAL_ACCESSORS(WasmInstanceObject, globals_buffer, JSArrayBuffer,
+                   kGlobalsBufferOffset)
+OPTIONAL_ACCESSORS(WasmInstanceObject, imported_mutable_globals_buffers,
+                   FixedArray, kImportedMutableGlobalsBuffersOffset)
 OPTIONAL_ACCESSORS(WasmInstanceObject, debug_info, WasmDebugInfo,
                    kDebugInfoOffset)
 OPTIONAL_ACCESSORS(WasmInstanceObject, table_object, WasmTableObject,
@@ -151,8 +151,8 @@ ACCESSORS(WasmInstanceObject, imported_function_callables, FixedArray,
           kImportedFunctionCallablesOffset)
 OPTIONAL_ACCESSORS(WasmInstanceObject, indirect_function_table_instances,
                    FixedArray, kIndirectFunctionTableInstancesOffset)
-ACCESSORS(WasmInstanceObject, managed_native_allocations, Foreign,
-          kManagedNativeAllocationsOffset)
+OPTIONAL_ACCESSORS(WasmInstanceObject, managed_native_allocations, Foreign,
+                   kManagedNativeAllocationsOffset)
 OPTIONAL_ACCESSORS(WasmInstanceObject, managed_indirect_patcher, Foreign,
                    kManagedIndirectPatcherOffset)
 
diff --git a/src/wasm/wasm-objects.h b/src/wasm/wasm-objects.h
index 644b48cb1f..b65f4649b2 100644
--- a/src/wasm/wasm-objects.h
+++ b/src/wasm/wasm-objects.h
@@ -298,6 +298,10 @@ class WasmInstanceObject : public JSObject {
   DECL_PRIMITIVE_ACCESSORS(indirect_function_table_sig_ids, uint32_t*)
   DECL_PRIMITIVE_ACCESSORS(indirect_function_table_targets, Address*)
 
+  // Dispatched behavior.
+  DECL_PRINTER(WasmInstanceObject)
+  DECL_VERIFIER(WasmInstanceObject)
+
 // Layout description.
 #define WASM_INSTANCE_OBJECT_FIELDS(V)                                  \
   V(kCompiledModuleOffset, kPointerSize)                                \