diff -up firefox-91.0.1/python/mozbuild/mozbuild/frontend/context.py.rhel7-nasm firefox-91.0.1/python/mozbuild/mozbuild/frontend/context.py
--- firefox-91.0.1/python/mozbuild/mozbuild/frontend/context.py.rhel7-nasm	2021-08-31 08:02:10.814740774 +0200
+++ firefox-91.0.1/python/mozbuild/mozbuild/frontend/context.py	2021-08-31 08:04:03.967146994 +0200
@@ -420,7 +420,7 @@ class AsmFlags(BaseCompileFlags):
                 if self._context.config.substs.get("OS_ARCH") == "WINNT":
                     debug_flags += ["-F", "cv8"]
                 elif self._context.config.substs.get("OS_ARCH") != "Darwin":
-                    debug_flags += ["-F", "dwarf"]
+                    debug_flags += ["-f", "elf32"]
             elif (
                 self._context.config.substs.get("OS_ARCH") == "WINNT"
                 and self._context.config.substs.get("CPU_ARCH") == "aarch64"