diff --git a/backprop/optimizer.cc b/backprop/optimizer.cc
index 4302f9c..673a96b 100644
--- a/backprop/optimizer.cc
+++ b/backprop/optimizer.cc
@@ -19,7 +19,6 @@
 #include <random>
 
 #include "gemma/common.h"
-#include "gemma/configs.h"
 #include "gemma/weights.h"
 #include "hwy/contrib/thread_pool/thread_pool.h"
 
diff --git a/gemma/gemma.cc b/gemma/gemma.cc
index ed8c36b..f0543bc 100644
--- a/gemma/gemma.cc
+++ b/gemma/gemma.cc
@@ -194,10 +194,8 @@ GemmaTokenizer::GemmaTokenizer(const Path& tokenizer_path) {
   impl_ = std::make_unique<Impl>(tokenizer_path);
 }
 
-GemmaTokenizer::GemmaTokenizer() {
-  impl_ = std::make_unique<Impl>();
-}
-
+// Default suffices, but they must be defined after GemmaTokenizer::Impl.
+GemmaTokenizer::GemmaTokenizer() = default;
 GemmaTokenizer::~GemmaTokenizer() = default;
 GemmaTokenizer::GemmaTokenizer(GemmaTokenizer&& other) = default;
 GemmaTokenizer& GemmaTokenizer::operator=(GemmaTokenizer&& other) = default;
diff --git a/gemma/run.cc b/gemma/run.cc
index af86dd8..3538184 100644
--- a/gemma/run.cc
+++ b/gemma/run.cc
@@ -35,10 +35,14 @@
 #include "hwy/highway.h"
 #include "hwy/per_target.h"
 #include "hwy/profiler.h"
+#include "hwy/timer.h"
 
 #if (!defined(HWY_VERSION_LT) || HWY_VERSION_LT(1, 2)) && !HWY_IDE
 #error "Please update to version 1.2 of github.com/google/highway."
 #endif
+#if HWY_CXX_LANG < 201703L
+#error "Gemma.cpp requires C++17, please pass -std=c++17."
+#endif
 
 static constexpr bool kVerboseLogTokens = false;
 
@@ -68,8 +72,12 @@ void ShowConfig(LoaderArgs& loader, InferenceArgs& inference, AppArgs& app) {
               << std::thread::hardware_concurrency() << "\n"
               << "Instruction set               : "
               << hwy::TargetName(hwy::DispatchedTarget()) << " ("
-              << hwy::VectorBytes() * 8 << " bits)" << "\n"
-              << "Compiled config               : " << CompiledConfig() << "\n"
+              << hwy::VectorBytes() * 8 << " bits)" << "\n";
+    char cpu100[100];
+    if (hwy::platform::GetCpuString(cpu100)) {
+      std::cout << "CPU                           : " << cpu100 << "\n";
+    }
+    std::cout << "Compiled config               : " << CompiledConfig() << "\n"
               << "Weight Type                   : "
               << gcpp::StringFromType(loader.WeightType()) << "\n"
               << "EmbedderInput Type            : "