diff -rauN firefox-99.0.1/modules/fdlibm/src/math_private.h firefox-99.0.1-fdlibm-double-patch/modules/fdlibm/src/math_private.h
--- firefox-99.0.1/modules/fdlibm/src/math_private.h	2022-04-12 00:00:09.000000000 +0200
+++ firefox-99.0.1-fdlibm-double-patch/modules/fdlibm/src/math_private.h	2022-04-25 16:47:00.697715429 +0200
@@ -30,7 +30,11 @@
  * Adapted from https://github.com/freebsd/freebsd-src/search?q=__double_t
  */
 
+#if defined __FLT_EVAL_METHOD__ && (__FLT_EVAL_METHOD__ == 2)
+typedef long double __double_t;
+#else
 typedef double      __double_t;
+#endif
 typedef __double_t  double_t;
 
 /*