diff --git a/security/sandbox/linux/moz.build b/security/sandbox/linux/moz.build
--- a/security/sandbox/linux/moz.build
+++ b/security/sandbox/linux/moz.build
@@ -114,9 +114,8 @@
 # gcc lto likes to put the top level asm in syscall.cc in a different partition
 # from the function using it which breaks the build.  Work around that by
 # forcing there to be only one partition.
-for f in CONFIG["OS_CXXFLAGS"]:
-    if f.startswith("-flto") and CONFIG["CC_TYPE"] != "clang":
-        LDFLAGS += ["--param lto-partitions=1"]
+if CONFIG['CC_TYPE'] != 'clang':
+    LDFLAGS += ['--param', 'lto-partitions=1']
 
 DEFINES["NS_NO_XPCOM"] = True
 DisableStlWrapping()