diff --git a/include/simdjson/generic/numberparsing.h b/include/simdjson/generic/numberparsing.h
index 771504bca..e0b1fa5fd 100644
--- a/include/simdjson/generic/numberparsing.h
+++ b/include/simdjson/generic/numberparsing.h
@@ -292,8 +292,9 @@ simdjson_really_inline bool compute_float_64(int64_t power, uint64_t i, bool neg
 // one digit.
 static bool parse_float_fallback(const uint8_t *ptr, double *outDouble) {
   *outDouble = simdjson::internal::from_chars((const char *)ptr);
-  // We do not accept infinite values.
-  if (!std::isfinite(*outDouble)) {
+  // We do not accept infinite values. Yes, there is a std::isfinite function, but
+  // it appears to be broken in legacy libc++.
+  if ((*outDouble > 0x1.fffffffffffffp+1023) || (*outDouble < -0x1.fffffffffffffp+1023)) {
     return false;
   }
   return true;
diff --git a/src/to_chars.cpp b/src/to_chars.cpp
index 45aa12cba..9860c9634 100644
--- a/src/to_chars.cpp
+++ b/src/to_chars.cpp
@@ -914,8 +914,13 @@ format. Returns an iterator pointing past-the-end of the decimal representation.
 */
 char *to_chars(char *first, const char *last, double value) {
   static_cast<void>(last); // maybe unused - fix warning
-  // Use signbit(value) instead of (value < 0) since signbit works for -0.
-  if (std::signbit(value)) {
+  // It would be better to use signbit(value) instead of (value < 0) since signbit works for -0.
+  //if(std::signbit(value)) {
+  //  value = -value;
+  //  *first++ = '-';
+  //}
+  // However, under older libc++, std::signbit causes build errors, so falling back:
+  if((value < 0) || (value == -0)){
     value = -value;
     *first++ = '-';
   }