diff --git a/src/reader/wgsl/lexer.cc b/src/reader/wgsl/lexer.cc
index 31d2546527..9aa3ae688a 100644
--- a/src/reader/wgsl/lexer.cc
+++ b/src/reader/wgsl/lexer.cc
@@ -14,6 +14,7 @@
 
 #include "src/reader/wgsl/lexer.h"
 
+#include <cctype>
 #include <cmath>
 #include <cstring>
 #include <limits>
diff --git a/src/utils/unique_vector.h b/src/utils/unique_vector.h
index ea29109aea..e56dd990f7 100644
--- a/src/utils/unique_vector.h
+++ b/src/utils/unique_vector.h
@@ -73,7 +73,7 @@ struct UniqueVector {
   const T& operator[](size_t i) const { return vector[i]; }
 
   /// @returns true if the vector is empty
-  size_t empty() const { return vector.empty(); }
+  bool empty() const { return vector.empty(); }
 
   /// @returns the number of items in the vector
   size_t size() const { return vector.size(); }