diff --git a/internal/cgen/base/strconv-public.h b/internal/cgen/base/strconv-public.h
index 861d9a4..8cde012 100644
--- a/internal/cgen/base/strconv-public.h
+++ b/internal/cgen/base/strconv-public.h
@@ -282,7 +282,12 @@
 
 // --------
 
+// WUFFS_BASE__I64__BYTE_LENGTH__MAX_INCL is the string length of
+// "-9223372036854775808" and "+9223372036854775807", INT64_MIN and INT64_MAX.
 #define WUFFS_BASE__I64__BYTE_LENGTH__MAX_INCL 20
+
+// WUFFS_BASE__U64__BYTE_LENGTH__MAX_INCL is the string length of
+// "+18446744073709551615", UINT64_MAX.
 #define WUFFS_BASE__U64__BYTE_LENGTH__MAX_INCL 21
 
 // wuffs_base__render_number_f64 writes the decimal encoding of x to dst and
diff --git a/internal/cgen/data/data.go b/internal/cgen/data/data.go
index f4629f0..3e6d7c9 100644
--- a/internal/cgen/data/data.go
+++ b/internal/cgen/data/data.go
@@ -533,10 +533,10 @@
 	"t64_t.\n//\n// It is similar to the C standard library's strtoull function, but:\n//  - Errors are returned in-band (in a result type), not out-of-band (errno).\n//  - It takes a slice (a pointer and length), not a NUL-terminated C string.\n//  - It does not take an optional endptr argument. It does not allow a partial\n//    parse: it returns an error unless all of s is consumed.\n//  - It does not allow whitespace, leading or otherwise.\n//  - It does not allow a leading '+' or '-'.\n//  - It does not take a base argument (e.g. base 10 vs base 16). Instead, it\n//    always accepts both decimal (e.g \"1234\", \"0d5678\") and hexadecimal (e.g.\n//    \"0x9aBC\"). The caller is responsible for prior filtering of e.g. hex\n//    numbers if they are unwanted. For example, Wuffs' JSON decoder will only\n//    produce a wuffs_base__token for decimal numbers, not hexadecimal.\n//  - It is not affected by i18n / l10n settings such as environment variables.\n//\n// The options argument can change these, but by default, it:\n//  - Rejects " +
 	"underscores. With an explicit opt-in, \"__0D_1_002\" would\n//    successfully parse as \"one thousand and two\". Underscores are still\n//    rejected inside the optional 2-byte opening \"0d\" or \"0X\" that denotes\n//    base-10 or base-16.\n//  - Rejects unnecessary leading zeroes: \"00\" and \"0644\".\n//\n// For modular builds that divide the base module into sub-modules, using this\n// function requires the WUFFS_CONFIG__MODULE__BASE__INTCONV sub-module, not\n// just WUFFS_CONFIG__MODULE__BASE__CORE.\nWUFFS_BASE__MAYBE_STATIC wuffs_base__result_u64  //\nwuffs_base__parse_number_u64(wuffs_base__slice_u8 s, uint32_t options);\n\n" +
 	"" +
-	"// --------\n\n#define WUFFS_BASE__I64__BYTE_LENGTH__MAX_INCL 20\n#define WUFFS_BASE__U64__BYTE_LENGTH__MAX_INCL 21\n\n// wuffs_base__render_number_f64 writes the decimal encoding of x to dst and\n// returns the number of bytes written. If dst is shorter than the entire\n// encoding, it returns 0 (and no bytes are written).\n//\n// For those familiar with C's printf or Go's fmt.Printf functions:\n//  - \"%e\" means the WUFFS_BASE__RENDER_NUMBER_FXX__EXPONENT_PRESENT option.\n//  - \"%f\" means the WUFFS_BASE__RENDER_NUMBER_FXX__EXPONENT_ABSENT  option.\n//  - \"%g\" means neither or both bits are set.\n//\n// The precision argument controls the number of digits rendered, excluding the\n// exponent (the \"e+05\" in \"1.23e+05\"):\n//  - for \"%e\" and \"%f\" it is the number of digits after the decimal separator,\n//  - for \"%g\" it is the number of significant digits (and trailing zeroes are\n//    removed).\n//\n// A precision of 6 gives similar output to printf's defaults.\n//\n// A precision greater than 4095 is equivalent to 4095.\n//\n// The " +
-	"precision argument is ignored when the\n// WUFFS_BASE__RENDER_NUMBER_FXX__JUST_ENOUGH_PRECISION option is set. This is\n// similar to Go's strconv.FormatFloat with a negative (i.e. non-sensical)\n// precision, but there is no corresponding feature in C's printf.\n//\n// Extreme values of x will be rendered as \"NaN\", \"Inf\" (or \"+Inf\" if the\n// WUFFS_BASE__RENDER_NUMBER_XXX__LEADING_PLUS_SIGN option is set) or \"-Inf\".\n//\n// For modular builds that divide the base module into sub-modules, using this\n// function requires the WUFFS_CONFIG__MODULE__BASE__FLOATCONV sub-module, not\n// just WUFFS_CONFIG__MODULE__BASE__CORE.\nWUFFS_BASE__MAYBE_STATIC size_t  //\nwuffs_base__render_number_f64(wuffs_base__slice_u8 dst,\n                              double x,\n                              uint32_t precision,\n                              uint32_t options);\n\n// wuffs_base__render_number_i64 writes the decimal encoding of x to dst and\n// returns the number of bytes written. If dst is shorter than the entire\n// encoding, it returns" +
-	" 0 (and no bytes are written).\n//\n// dst will never be too short if its length is at least 20, also known as\n// WUFFS_BASE__I64__BYTE_LENGTH__MAX_INCL.\n//\n// For modular builds that divide the base module into sub-modules, using this\n// function requires the WUFFS_CONFIG__MODULE__BASE__INTCONV sub-module, not\n// just WUFFS_CONFIG__MODULE__BASE__CORE.\nWUFFS_BASE__MAYBE_STATIC size_t  //\nwuffs_base__render_number_i64(wuffs_base__slice_u8 dst,\n                              int64_t x,\n                              uint32_t options);\n\n// wuffs_base__render_number_u64 writes the decimal encoding of x to dst and\n// returns the number of bytes written. If dst is shorter than the entire\n// encoding, it returns 0 (and no bytes are written).\n//\n// dst will never be too short if its length is at least 21, also known as\n// WUFFS_BASE__U64__BYTE_LENGTH__MAX_INCL.\n//\n// For modular builds that divide the base module into sub-modules, using this\n// function requires the WUFFS_CONFIG__MODULE__BASE__INTCONV sub-module, not\n// " +
-	"just WUFFS_CONFIG__MODULE__BASE__CORE.\nWUFFS_BASE__MAYBE_STATIC size_t  //\nwuffs_base__render_number_u64(wuffs_base__slice_u8 dst,\n                              uint64_t x,\n                              uint32_t options);\n\n" +
+	"// --------\n\n// WUFFS_BASE__I64__BYTE_LENGTH__MAX_INCL is the string length of\n// \"-9223372036854775808\" and \"+9223372036854775807\", INT64_MIN and INT64_MAX.\n#define WUFFS_BASE__I64__BYTE_LENGTH__MAX_INCL 20\n\n// WUFFS_BASE__U64__BYTE_LENGTH__MAX_INCL is the string length of\n// \"+18446744073709551615\", UINT64_MAX.\n#define WUFFS_BASE__U64__BYTE_LENGTH__MAX_INCL 21\n\n// wuffs_base__render_number_f64 writes the decimal encoding of x to dst and\n// returns the number of bytes written. If dst is shorter than the entire\n// encoding, it returns 0 (and no bytes are written).\n//\n// For those familiar with C's printf or Go's fmt.Printf functions:\n//  - \"%e\" means the WUFFS_BASE__RENDER_NUMBER_FXX__EXPONENT_PRESENT option.\n//  - \"%f\" means the WUFFS_BASE__RENDER_NUMBER_FXX__EXPONENT_ABSENT  option.\n//  - \"%g\" means neither or both bits are set.\n//\n// The precision argument controls the number of digits rendered, excluding the\n// exponent (the \"e+05\" in \"1.23e+05\"):\n//  - for \"%e\" and \"%f\" it is the number of digits after t" +
+	"he decimal separator,\n//  - for \"%g\" it is the number of significant digits (and trailing zeroes are\n//    removed).\n//\n// A precision of 6 gives similar output to printf's defaults.\n//\n// A precision greater than 4095 is equivalent to 4095.\n//\n// The precision argument is ignored when the\n// WUFFS_BASE__RENDER_NUMBER_FXX__JUST_ENOUGH_PRECISION option is set. This is\n// similar to Go's strconv.FormatFloat with a negative (i.e. non-sensical)\n// precision, but there is no corresponding feature in C's printf.\n//\n// Extreme values of x will be rendered as \"NaN\", \"Inf\" (or \"+Inf\" if the\n// WUFFS_BASE__RENDER_NUMBER_XXX__LEADING_PLUS_SIGN option is set) or \"-Inf\".\n//\n// For modular builds that divide the base module into sub-modules, using this\n// function requires the WUFFS_CONFIG__MODULE__BASE__FLOATCONV sub-module, not\n// just WUFFS_CONFIG__MODULE__BASE__CORE.\nWUFFS_BASE__MAYBE_STATIC size_t  //\nwuffs_base__render_number_f64(wuffs_base__slice_u8 dst,\n                              double x,\n                      " +
+	"        uint32_t precision,\n                              uint32_t options);\n\n// wuffs_base__render_number_i64 writes the decimal encoding of x to dst and\n// returns the number of bytes written. If dst is shorter than the entire\n// encoding, it returns 0 (and no bytes are written).\n//\n// dst will never be too short if its length is at least 20, also known as\n// WUFFS_BASE__I64__BYTE_LENGTH__MAX_INCL.\n//\n// For modular builds that divide the base module into sub-modules, using this\n// function requires the WUFFS_CONFIG__MODULE__BASE__INTCONV sub-module, not\n// just WUFFS_CONFIG__MODULE__BASE__CORE.\nWUFFS_BASE__MAYBE_STATIC size_t  //\nwuffs_base__render_number_i64(wuffs_base__slice_u8 dst,\n                              int64_t x,\n                              uint32_t options);\n\n// wuffs_base__render_number_u64 writes the decimal encoding of x to dst and\n// returns the number of bytes written. If dst is shorter than the entire\n// encoding, it returns 0 (and no bytes are written).\n//\n// dst will never be too sho" +
+	"rt if its length is at least 21, also known as\n// WUFFS_BASE__U64__BYTE_LENGTH__MAX_INCL.\n//\n// For modular builds that divide the base module into sub-modules, using this\n// function requires the WUFFS_CONFIG__MODULE__BASE__INTCONV sub-module, not\n// just WUFFS_CONFIG__MODULE__BASE__CORE.\nWUFFS_BASE__MAYBE_STATIC size_t  //\nwuffs_base__render_number_u64(wuffs_base__slice_u8 dst,\n                              uint64_t x,\n                              uint32_t options);\n\n" +
 	"" +
 	"// ---------------- Base-16\n\n// Options (bitwise or'ed together) for wuffs_base__base_16__xxx functions.\n\n#define WUFFS_BASE__BASE_16__DEFAULT_OPTIONS ((uint32_t)0x00000000)\n\n// wuffs_base__base_16__decode2 converts \"6A6b\" to \"jk\", where e.g. 'j' is\n// U+006A. There are 2 src bytes for every dst byte.\n//\n// It assumes that the src bytes are two hexadecimal digits (0-9, A-F, a-f),\n// repeated. It may write nonsense bytes if not, although it will not read or\n// write out of bounds.\n//\n// For modular builds that divide the base module into sub-modules, using this\n// function requires the WUFFS_CONFIG__MODULE__BASE__INTCONV sub-module, not\n// just WUFFS_CONFIG__MODULE__BASE__CORE.\nWUFFS_BASE__MAYBE_STATIC wuffs_base__transform__output  //\nwuffs_base__base_16__decode2(wuffs_base__slice_u8 dst,\n                             wuffs_base__slice_u8 src,\n                             bool src_closed,\n                             uint32_t options);\n\n// wuffs_base__base_16__decode4 converts both \"\\\\x6A\\\\x6b\" and \"??6a??6B\" " +
 	"to\n// \"jk\", where e.g. 'j' is U+006A. There are 4 src bytes for every dst byte.\n//\n// It assumes that the src bytes are two ignored bytes and then two hexadecimal\n// digits (0-9, A-F, a-f), repeated. It may write nonsense bytes if not,\n// although it will not read or write out of bounds.\n//\n// For modular builds that divide the base module into sub-modules, using this\n// function requires the WUFFS_CONFIG__MODULE__BASE__INTCONV sub-module, not\n// just WUFFS_CONFIG__MODULE__BASE__CORE.\nWUFFS_BASE__MAYBE_STATIC wuffs_base__transform__output  //\nwuffs_base__base_16__decode4(wuffs_base__slice_u8 dst,\n                             wuffs_base__slice_u8 src,\n                             bool src_closed,\n                             uint32_t options);\n\n// wuffs_base__base_16__encode2 converts \"jk\" to \"6A6B\", where e.g. 'j' is\n// U+006A. There are 2 dst bytes for every src byte.\n//\n// For modular builds that divide the base module into sub-modules, using this\n// function requires the WUFFS_CONFIG__MODULE__BASE__INTCONV" +
diff --git a/release/c/wuffs-unsupported-snapshot.c b/release/c/wuffs-unsupported-snapshot.c
index e9dcd84..d3be633 100644
--- a/release/c/wuffs-unsupported-snapshot.c
+++ b/release/c/wuffs-unsupported-snapshot.c
@@ -4205,7 +4205,12 @@
 
 // --------
 
+// WUFFS_BASE__I64__BYTE_LENGTH__MAX_INCL is the string length of
+// "-9223372036854775808" and "+9223372036854775807", INT64_MIN and INT64_MAX.
 #define WUFFS_BASE__I64__BYTE_LENGTH__MAX_INCL 20
+
+// WUFFS_BASE__U64__BYTE_LENGTH__MAX_INCL is the string length of
+// "+18446744073709551615", UINT64_MAX.
 #define WUFFS_BASE__U64__BYTE_LENGTH__MAX_INCL 21
 
 // wuffs_base__render_number_f64 writes the decimal encoding of x to dst and