diff --git a/core/fxcrt/cfx_bitstream_unittest.cpp b/core/fxcrt/cfx_bitstream_unittest.cpp
index 4ca380c..9debbd0 100644
--- a/core/fxcrt/cfx_bitstream_unittest.cpp
+++ b/core/fxcrt/cfx_bitstream_unittest.cpp
@@ -158,9 +158,10 @@
   // We can't actually allocate enough memory to test the limits of
   // the bitstream arithmetic, but as long as we don't try to extract
   // any bits, the calculations should be unaffected.
+  const uint8_t kNotReallyBigEnough[32] = {};
   constexpr size_t kAllocationBytes = std::numeric_limits<size_t>::max() / 8;
   constexpr size_t kAllocationBits = kAllocationBytes * 8;
-  CFX_BitStream bitstream({nullptr, kAllocationBytes});
+  CFX_BitStream bitstream({kNotReallyBigEnough, kAllocationBytes});
   EXPECT_FALSE(bitstream.IsEOF());
   EXPECT_EQ(0U, bitstream.GetPos());
   EXPECT_EQ(kAllocationBits, bitstream.BitsRemaining());
diff --git a/third_party/base/span.h b/third_party/base/span.h
index b19544a..f819e92 100644
--- a/third_party/base/span.h
+++ b/third_party/base/span.h
@@ -189,7 +189,9 @@
 
   // [span.cons], span constructors, copy, assignment, and destructor
   constexpr span() noexcept : data_(nullptr), size_(0) {}
-  constexpr span(T* data, size_t size) noexcept : data_(data), size_(size) {}
+  constexpr span(T* data, size_t size) noexcept : data_(data), size_(size) {
+    DCHECK(data_ || size_ == 0);
+  }
 
   // TODO(dcheng): Implement construction from a |begin| and |end| pointer.
   template <size_t N>