The custom pow()-based real-number conversion was historical: when this code was written, wine could not link against ucrtbase, so the lexer reimplemented the conversion. That constraint is gone, and the custom code had two correctness gaps - subnormal literals (e.g. 1e-309) rounded to zero because pow(10, 309) overflows to infinity, and values near DBL_MAX could round through the same infinity edge. Hand the literal span to _wcstod_l with a C locale instead, which handles rounding, subnormals, and overflow per IEEE 754 - and is locale-invariant by construction, matching VBScript source semantics where the decimal separator is always '.' regardless of runtime SetLocale. Above-DBL_MAX literals (1e309, 1.8e308) continue to raise err 1031 as before. alternative for !10898 supersedes !7591 -- v5: vbscript: Parse double literals via ucrtbase _wcstod_l. https://gitlab.winehq.org/wine/wine/-/merge_requests/10937