diff --git a/include/fmt/format.h b/include/fmt/format.h
index dbf92f1a..cd43119d 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -2249,7 +2249,7 @@ FMT_CONSTEXPR20 auto do_write_float(OutputIt out, const DecimalFP& fp,
       if (num_zeros > 0) size += to_unsigned(num_zeros);
     }
     auto grouping = Grouping(loc, fspecs.locale);
-    size += to_unsigned(grouping.count_separators(significand_size));
+    size += to_unsigned(grouping.count_separators(exp));
     return write_padded<align::right>(out, specs, size, [&](iterator it) {
       if (sign) *it++ = detail::sign<Char>(sign);
       it = write_significand<Char>(it, significand, significand_size,
diff --git a/test/xchar-test.cc b/test/xchar-test.cc
index 4386e8b9..0b0df9e3 100644
--- a/test/xchar-test.cc
+++ b/test/xchar-test.cc
@@ -370,10 +370,11 @@ template <typename Char> struct small_grouping : std::numpunct<Char> {
 
 TEST(locale_test, localized_double) {
   auto loc = std::locale(std::locale(), new numpunct<char>());
-  EXPECT_EQ("1?23", fmt::format(loc, "{:L}", 1.23));
-  EXPECT_EQ("1?230000", fmt::format(loc, "{:Lf}", 1.23));
-  EXPECT_EQ("1~234?5", fmt::format(loc, "{:L}", 1234.5));
-  EXPECT_EQ("12~000", fmt::format(loc, "{:L}", 12000.0));
+  EXPECT_EQ(fmt::format(loc, "{:L}", 1.23), "1?23");
+  EXPECT_EQ(fmt::format(loc, "{:Lf}", 1.23), "1?230000");
+  EXPECT_EQ(fmt::format(loc, "{:L}", 1234.5), "1~234?5");
+  EXPECT_EQ(fmt::format(loc, "{:L}", 12000.0), "12~000");
+  EXPECT_EQ(fmt::format(loc, "{:8L}", 1230.0), "   1~230");
 }
 
 TEST(locale_test, format) {