diff --git a/cppformat/format.cc b/cppformat/format.cc
index 0857965e..908a5156 100644
--- a/cppformat/format.cc
+++ b/cppformat/format.cc
@@ -257,7 +257,7 @@ class WidthHandler : public fmt::internal::ArgVisitor<WidthHandler, unsigned> {
   template <typename T>
   unsigned visit_any_int(T value) {
     typedef typename fmt::internal::IntTraits<T>::MainType UnsignedType;
-    UnsignedType width = value;
+    UnsignedType width = static_cast<UnsignedType>(value);
     if (fmt::internal::is_negative(value)) {
       spec_.align_ = fmt::ALIGN_LEFT;
       width = 0 - width;
@@ -336,7 +336,7 @@ class ArgConverter : public fmt::internal::ArgVisitor<ArgConverter<T>, void> {
         // glibc's printf doesn't sign extend arguments of smaller types:
         //   std::printf("%lld", -42);  // prints "4294967254"
         // but we don't have to do the same because it's a UB.
-        arg_.long_long_value = value;
+        arg_.long_long_value = static_cast<fmt::LongLong>(value);
       } else {
         arg_.type = Arg::ULONG_LONG;
         arg_.ulong_long_value =
@@ -786,7 +786,7 @@ void fmt::internal::PrintfFormatter<Char>::format(
     if (*s == '.') {
       ++s;
       if ('0' <= *s && *s <= '9') {
-        spec.precision_ = parse_nonnegative_int(s);
+        spec.precision_ = static_cast<int>(parse_nonnegative_int(s));
       } else if (*s == '*') {
         ++s;
         spec.precision_ = PrecisionHandler().visit(get_arg(s));
@@ -795,7 +795,7 @@ void fmt::internal::PrintfFormatter<Char>::format(
 
     Arg arg = get_arg(s, arg_index);
     if (spec.flag(HASH_FLAG) && IsZeroInt().visit(arg))
-      spec.flags_ &= ~HASH_FLAG;
+      spec.flags_ &= ~to_unsigned<int>(HASH_FLAG);
     if (spec.fill_ == '0') {
       if (arg.type <= Arg::LAST_NUMERIC_TYPE)
         spec.align_ = ALIGN_NUMERIC;
diff --git a/cppformat/format.h b/cppformat/format.h
index 9f81bb4a..22be015b 100644
--- a/cppformat/format.h
+++ b/cppformat/format.h
@@ -1832,7 +1832,7 @@ class FormatterBase {
   // Returns the next argument.
   Arg next_arg(const char *&error) {
     if (next_arg_index_ >= 0)
-      return do_get_arg(static_cast<unsigned>(next_arg_index_++), error);
+      return do_get_arg(internal::to_unsigned(next_arg_index_++), error);
     error = "cannot switch from manual to automatic argument indexing";
     return Arg();
   }
@@ -2245,7 +2245,8 @@ class BasicWriter {
   // Writes a decimal integer.
   template <typename Int>
   void write_decimal(Int value) {
-    typename internal::IntTraits<Int>::MainType abs_value = value;
+    typedef typename internal::IntTraits<Int>::MainType MainType;
+    MainType abs_value = static_cast<MainType>(value);
     if (internal::is_negative(value)) {
       abs_value = 0 - abs_value;
       *write_unsigned_decimal(abs_value, 1) = '-';
@@ -2548,7 +2549,8 @@ typename BasicWriter<Char>::CharPtr
     // is specified.
     if (prefix_size > 0 && prefix[prefix_size - 1] == '0')
       --prefix_size;
-    unsigned number_size = prefix_size + spec.precision();
+    unsigned number_size =
+        prefix_size + internal::to_unsigned(spec.precision());
     AlignSpec subspec(number_size, '0', ALIGN_NUMERIC);
     if (number_size >= width)
       return prepare_int_buffer(num_digits, subspec, prefix, prefix_size);
@@ -3430,7 +3432,7 @@ inline bool is_name_start(Char c) {
 // Parses an unsigned integer advancing s to the end of the parsed input.
 // This function assumes that the first character of s is a digit.
 template <typename Char>
-int parse_nonnegative_int(const Char *&s) {
+unsigned parse_nonnegative_int(const Char *&s) {
   assert('0' <= *s && *s <= '9');
   unsigned value = 0;
   do {