diff --git a/src/format.cc b/src/format.cc
index 9a9abf8d0a73..1e98bc802f59 100644
--- a/src/format.cc
+++ b/src/format.cc
@@ -29,7 +29,7 @@ struct sprintf_specs {
   bool alt : 1;
 
   template <typename Char>
-  constexpr sprintf_specs(basic_format_specs<Char> specs)
+  constexpr explicit sprintf_specs(basic_format_specs<Char> specs)
       : precision(specs.precision), type(specs.type), alt(specs.alt) {}
 
   constexpr bool has_precision() const { return precision >= 0; }
@@ -81,7 +81,8 @@ char* sprintf_format(Double value, internal::buffer<char>& buf,
       unsigned n = internal::to_unsigned(result);
       if (n < buf.capacity()) {
         // Find the decimal point.
-        auto p = buf.data(), end = p + n;
+        auto *p = buf.data();
+        auto *end = p + n;
         if (*p == '+' || *p == '-') ++p;
         if (specs.type != 'a' && specs.type != 'A') {
           while (p < end && *p >= '0' && *p <= '9') ++p;