diff --git a/libcxx/include/__format/parser_std_format_spec.h b/libcxx/include/__format/parser_std_format_spec.h
--- a/libcxx/include/__format/parser_std_format_spec.h
+++ b/libcxx/include/__format/parser_std_format_spec.h
@@ -214,7 +214,7 @@
       __format::__parse_arg_id(__begin, __end, __parse_ctx);
 
   if (__r.__ptr == __end || *__r.__ptr != _CharT('}'))
-    __throw_format_error("A format-spec arg-id should terminate at a '}'");
+    __throw_format_error("Invalid arg-id");
 
   ++__r.__ptr;
   return __r;
diff --git a/libcxx/test/libcxx/utilities/format/format.string/format.string.std/std_format_spec_bool.pass.cpp b/libcxx/test/libcxx/utilities/format/format.string/format.string.std/std_format_spec_bool.pass.cpp
--- a/libcxx/test/libcxx/utilities/format/format.string/format.string.std/std_format_spec_bool.pass.cpp
+++ b/libcxx/test/libcxx/utilities/format/format.string/format.string.std/std_format_spec_bool.pass.cpp
@@ -160,19 +160,14 @@
 
   test_exception<Parser<CharT>>("End of input while parsing format-spec arg-id",
                                 CSTR("{"));
-  test_exception<Parser<CharT>>(
-      "A format-spec arg-id should terminate at a '}'", CSTR("{0"));
+  test_exception<Parser<CharT>>("Invalid arg-id", CSTR("{0"));
   test_exception<Parser<CharT>>(
       "The arg-id of the format-spec starts with an invalid character",
       CSTR("{a"));
-  test_exception<Parser<CharT>>(
-      "A format-spec arg-id should terminate at a '}'", CSTR("{1"));
-  test_exception<Parser<CharT>>(
-      "A format-spec arg-id should terminate at a '}'", CSTR("{9"));
-  test_exception<Parser<CharT>>(
-      "A format-spec arg-id should terminate at a '}'", CSTR("{9:"));
-  test_exception<Parser<CharT>>(
-      "A format-spec arg-id should terminate at a '}'", CSTR("{9a"));
+  test_exception<Parser<CharT>>("Invalid arg-id", CSTR("{1"));
+  test_exception<Parser<CharT>>("Invalid arg-id", CSTR("{9"));
+  test_exception<Parser<CharT>>("Invalid arg-id", CSTR("{9:"));
+  test_exception<Parser<CharT>>("Invalid arg-id", CSTR("{9a"));
 
   static_assert(std::__format::__number_max == 2'147'483'647,
                 "Update the assert and the test.");
diff --git a/libcxx/test/libcxx/utilities/format/format.string/format.string.std/std_format_spec_char.pass.cpp b/libcxx/test/libcxx/utilities/format/format.string/format.string.std/std_format_spec_char.pass.cpp
--- a/libcxx/test/libcxx/utilities/format/format.string/format.string.std/std_format_spec_char.pass.cpp
+++ b/libcxx/test/libcxx/utilities/format/format.string/format.string.std/std_format_spec_char.pass.cpp
@@ -169,19 +169,14 @@
 
   test_exception<Parser<CharT>>("End of input while parsing format-spec arg-id",
                                 CSTR("{"));
-  test_exception<Parser<CharT>>(
-      "A format-spec arg-id should terminate at a '}'", CSTR("{0"));
+  test_exception<Parser<CharT>>("Invalid arg-id", CSTR("{0"));
   test_exception<Parser<CharT>>(
       "The arg-id of the format-spec starts with an invalid character",
       CSTR("{a"));
-  test_exception<Parser<CharT>>(
-      "A format-spec arg-id should terminate at a '}'", CSTR("{1"));
-  test_exception<Parser<CharT>>(
-      "A format-spec arg-id should terminate at a '}'", CSTR("{9"));
-  test_exception<Parser<CharT>>(
-      "A format-spec arg-id should terminate at a '}'", CSTR("{9:"));
-  test_exception<Parser<CharT>>(
-      "A format-spec arg-id should terminate at a '}'", CSTR("{9a"));
+  test_exception<Parser<CharT>>("Invalid arg-id", CSTR("{1"));
+  test_exception<Parser<CharT>>("Invalid arg-id", CSTR("{9"));
+  test_exception<Parser<CharT>>("Invalid arg-id", CSTR("{9:"));
+  test_exception<Parser<CharT>>("Invalid arg-id", CSTR("{9a"));
 
   static_assert(std::__format::__number_max == 2'147'483'647,
                 "Update the assert and the test.");
diff --git a/libcxx/test/libcxx/utilities/format/format.string/format.string.std/std_format_spec_integer.pass.cpp b/libcxx/test/libcxx/utilities/format/format.string/format.string.std/std_format_spec_integer.pass.cpp
--- a/libcxx/test/libcxx/utilities/format/format.string/format.string.std/std_format_spec_integer.pass.cpp
+++ b/libcxx/test/libcxx/utilities/format/format.string/format.string.std/std_format_spec_integer.pass.cpp
@@ -209,19 +209,14 @@
 
   test_exception<Parser<CharT>>("End of input while parsing format-spec arg-id",
                                 CSTR("{"));
-  test_exception<Parser<CharT>>(
-      "A format-spec arg-id should terminate at a '}'", CSTR("{0"));
+  test_exception<Parser<CharT>>("Invalid arg-id", CSTR("{0"));
   test_exception<Parser<CharT>>(
       "The arg-id of the format-spec starts with an invalid character",
       CSTR("{a"));
-  test_exception<Parser<CharT>>(
-      "A format-spec arg-id should terminate at a '}'", CSTR("{1"));
-  test_exception<Parser<CharT>>(
-      "A format-spec arg-id should terminate at a '}'", CSTR("{9"));
-  test_exception<Parser<CharT>>(
-      "A format-spec arg-id should terminate at a '}'", CSTR("{9:"));
-  test_exception<Parser<CharT>>(
-      "A format-spec arg-id should terminate at a '}'", CSTR("{9a"));
+  test_exception<Parser<CharT>>("Invalid arg-id", CSTR("{1"));
+  test_exception<Parser<CharT>>("Invalid arg-id", CSTR("{9"));
+  test_exception<Parser<CharT>>("Invalid arg-id", CSTR("{9:"));
+  test_exception<Parser<CharT>>("Invalid arg-id", CSTR("{9a"));
 
   static_assert(std::__format::__number_max == 2'147'483'647,
                 "Update the assert and the test.");
diff --git a/libcxx/test/libcxx/utilities/format/format.string/format.string.std/std_format_spec_string.pass.cpp b/libcxx/test/libcxx/utilities/format/format.string/format.string.std/std_format_spec_string.pass.cpp
--- a/libcxx/test/libcxx/utilities/format/format.string/format.string.std/std_format_spec_string.pass.cpp
+++ b/libcxx/test/libcxx/utilities/format/format.string/format.string.std/std_format_spec_string.pass.cpp
@@ -164,19 +164,14 @@
 
   test_exception<Parser<CharT>>("End of input while parsing format-spec arg-id",
                                 CSTR("{"));
-  test_exception<Parser<CharT>>(
-      "A format-spec arg-id should terminate at a '}'", CSTR("{0"));
+  test_exception<Parser<CharT>>("Invalid arg-id", CSTR("{0"));
   test_exception<Parser<CharT>>(
       "The arg-id of the format-spec starts with an invalid character",
       CSTR("{a"));
-  test_exception<Parser<CharT>>(
-      "A format-spec arg-id should terminate at a '}'", CSTR("{1"));
-  test_exception<Parser<CharT>>(
-      "A format-spec arg-id should terminate at a '}'", CSTR("{9"));
-  test_exception<Parser<CharT>>(
-      "A format-spec arg-id should terminate at a '}'", CSTR("{9:"));
-  test_exception<Parser<CharT>>(
-      "A format-spec arg-id should terminate at a '}'", CSTR("{9a"));
+  test_exception<Parser<CharT>>("Invalid arg-id", CSTR("{1"));
+  test_exception<Parser<CharT>>("Invalid arg-id", CSTR("{9"));
+  test_exception<Parser<CharT>>("Invalid arg-id", CSTR("{9:"));
+  test_exception<Parser<CharT>>("Invalid arg-id", CSTR("{9a"));
 
   static_assert(std::__format::__number_max == 2'147'483'647,
                 "Update the assert and the test.");
@@ -226,19 +221,14 @@
 
   test_exception<Parser<CharT>>("End of input while parsing format-spec arg-id",
                                 CSTR(".{"));
-  test_exception<Parser<CharT>>(
-      "A format-spec arg-id should terminate at a '}'", CSTR(".{0"));
+  test_exception<Parser<CharT>>("Invalid arg-id", CSTR(".{0"));
   test_exception<Parser<CharT>>(
       "The arg-id of the format-spec starts with an invalid character",
       CSTR(".{a"));
-  test_exception<Parser<CharT>>(
-      "A format-spec arg-id should terminate at a '}'", CSTR(".{1"));
-  test_exception<Parser<CharT>>(
-      "A format-spec arg-id should terminate at a '}'", CSTR(".{9"));
-  test_exception<Parser<CharT>>(
-      "A format-spec arg-id should terminate at a '}'", CSTR(".{9:"));
-  test_exception<Parser<CharT>>(
-      "A format-spec arg-id should terminate at a '}'", CSTR(".{9a"));
+  test_exception<Parser<CharT>>("Invalid arg-id", CSTR(".{1"));
+  test_exception<Parser<CharT>>("Invalid arg-id", CSTR(".{9"));
+  test_exception<Parser<CharT>>("Invalid arg-id", CSTR(".{9:"));
+  test_exception<Parser<CharT>>("Invalid arg-id", CSTR(".{9a"));
 
   static_assert(std::__format::__number_max == 2'147'483'647,
                 "Update the assert and the test.");
diff --git a/libcxx/test/std/utilities/format/format.functions/format_tests.h b/libcxx/test/std/utilities/format/format.functions/format_tests.h
--- a/libcxx/test/std/utilities/format/format.functions/format_tests.h
+++ b/libcxx/test/std/utilities/format/format.functions/format_tests.h
@@ -176,9 +176,7 @@
       "Using automatic argument numbering in manual argument numbering mode",
       STR("hello {0:{}}"), world, 1);
   // Arg-id may not have leading zeros.
-  check_exception(
-      "A format-spec arg-id should terminate at a '}'",
-      STR("hello {0:{01}}"), world, 1);
+  check_exception("Invalid arg-id", STR("hello {0:{01}}"), world, 1);
 
   // *** precision ***
 #if _LIBCPP_VERSION
@@ -214,9 +212,7 @@
       "Using automatic argument numbering in manual argument numbering mode",
       STR("hello {0:.{}}"), world, 1);
   // Arg-id may not have leading zeros.
-  check_exception(
-      "A format-spec arg-id should terminate at a '}'",
-      STR("hello {0:.{01}}"), world, 1);
+  check_exception("Invalid arg-id", STR("hello {0:.{01}}"), world, 1);
 
   // *** locale-specific form ***
   check_exception("The format-spec should consume the input or end with a '}'",