diff --git a/BUILD.bazel b/BUILD.bazel
index 8c32631..f4aed0d 100644
--- a/BUILD.bazel
+++ b/BUILD.bazel
@@ -265,10 +265,10 @@ cc_library(
         "gemma/tensor_index.h",
     ],
     deps = [
+        ":basics",
         "//compression:fields",
         "//compression:sfp",
         "@highway//:hwy",  # base.h
-        "@highway//:thread_pool",
     ],
 )
 
diff --git a/compression/fields.cc b/compression/fields.cc
index 8977af7..092597f 100644
--- a/compression/fields.cc
+++ b/compression/fields.cc
@@ -24,7 +24,6 @@
 #include <string>
 #include <vector>
 
-#include "hwy/aligned_allocator.h"
 #include "hwy/base.h"
 
 namespace gcpp {
@@ -115,7 +114,7 @@ class PrintVisitor : public VisitorBase {
 
 class ReadVisitor : public VisitorBase {
  public:
-  ReadVisitor(const hwy::Span<const uint32_t>& span, size_t pos)
+  ReadVisitor(const SerializedSpan span, size_t pos)
       : span_(span), result_(pos) {}
   ~ReadVisitor() {
     HWY_ASSERT(end_.empty());  // Bug if push/pop are not balanced.
@@ -236,7 +235,7 @@ class ReadVisitor : public VisitorBase {
   }
 
  private:
-  const hwy::Span<const uint32_t> span_;
+  const SerializedSpan span_;
   IFields::ReadResult result_;
   // Stack of end positions of nested IFields. Updated in operator()(IFields&),
   // but read in SkipField.
@@ -326,8 +325,7 @@ void IFields::Print() const {
   visitor(*const_cast<IFields*>(this));
 }
 
-IFields::ReadResult IFields::Read(const hwy::Span<const uint32_t>& span,
-                                  size_t pos) {
+IFields::ReadResult IFields::Read(const SerializedSpan span, size_t pos) {
   ReadVisitor visitor(span, pos);
   visitor(*this);
   return visitor.Result();
diff --git a/compression/fields.h b/compression/fields.h
index a17b48c..57465c4 100644
--- a/compression/fields.h
+++ b/compression/fields.h
@@ -27,7 +27,7 @@
 #include <string>
 #include <vector>
 
-#include "hwy/aligned_allocator.h"
+#include "hwy/aligned_allocator.h"  // Span
 #include "hwy/base.h"
 // IWYU pragma: end_exports
 
@@ -133,6 +133,8 @@ class IFieldsVisitor {
   bool any_invalid_ = false;
 };
 
+using SerializedSpan = hwy::Span<const uint32_t>;
+
 // Abstract base class for user-defined serializable classes, which are
 // forward- and backward compatible collection of fields (members). This means
 // old code can safely read new data, and new code can still handle old data.
@@ -178,13 +180,13 @@ struct IFields {
     // the code, but valid, and extra_u32 should be zero.
     uint32_t missing_fields;
     // How many extra u32 are in the stored size, vs. what we actually read as
-    // requested by VisitFields. If non-zero,, the data is newer than the code,
+    // requested by VisitFields. If non-zero, the data is newer than the code,
     // but valid, and missing_fields should be zero.
     uint32_t extra_u32;
   };
 
   // Reads fields starting at `span[pos]`.
-  ReadResult Read(const hwy::Span<const uint32_t>& span, size_t pos);
+  ReadResult Read(SerializedSpan span, size_t pos);
 
   // Returns false if there was an unrecoverable error, typically because a
   // field has an invalid value. If so, `storage` is undefined.
diff --git a/gemma/common.cc b/gemma/common.cc
index 0d8977b..da782c5 100644
--- a/gemma/common.cc
+++ b/gemma/common.cc
@@ -24,9 +24,8 @@
 #include <string>
 #include <vector>
 
-#include "compression/shared.h"
+#include "util/basics.h"  // BF16
 #include "hwy/base.h"
-#include "hwy/contrib/thread_pool/thread_pool.h"
 
 namespace gcpp {
 
@@ -162,8 +161,8 @@ void Wrap(const ModelInfo& info, size_t pos, std::string& prompt) {
 
 float EmbeddingScaling(size_t model_dim) {
   // Round to bf16 to match Gemma's Embedder, which casts before mul.
-  return hwy::ConvertScalarTo<float>(hwy::ConvertScalarTo<hwy::bfloat16_t>(
-      sqrtf(static_cast<float>(model_dim))));
+  return hwy::ConvertScalarTo<float>(
+      hwy::ConvertScalarTo<BF16>(sqrtf(static_cast<float>(model_dim))));
 }
 
 float ChooseQueryScale(const ModelConfig& config) {
diff --git a/gemma/common.h b/gemma/common.h
index 984b0ba..8aa2112 100644
--- a/gemma/common.h
+++ b/gemma/common.h
@@ -20,9 +20,9 @@
 
 #include <string>
 
-#include "compression/shared.h"  // PromptWrapping
-#include "gemma/configs.h"  // IWYU pragma: export
-#include "hwy/base.h"  // ConvertScalarTo
+#include "compression/shared.h"  // Type
+#include "gemma/configs.h"       // IWYU pragma: export
+#include "hwy/base.h"              // ConvertScalarTo
 
 namespace gcpp {
 
diff --git a/util/basics.h b/util/basics.h
index b8f2735..40545fd 100644
--- a/util/basics.h
+++ b/util/basics.h
@@ -67,10 +67,7 @@ struct TokenAndProb {
 // Entire size of a 2D array.
 struct Extents2D {
   constexpr Extents2D() : rows(0), cols(0) {}
-  constexpr Extents2D(size_t rows, size_t cols) : rows(rows), cols(cols) {
-    HWY_DASSERT(rows != 0);
-    HWY_DASSERT(cols != 0);
-  }
+  constexpr Extents2D(size_t rows, size_t cols) : rows(rows), cols(cols) {}
 
   size_t Area() const { return rows * cols; }