diff --git a/lib/asan/asan_internal.h b/lib/asan/asan_internal.h
index d34884c..ca62d40 100644
--- a/lib/asan/asan_internal.h
+++ b/lib/asan/asan_internal.h
@@ -91,7 +91,6 @@
 extern int    FLAG_demangle;
 extern bool   FLAG_symbolize;
 extern int    FLAG_v;
-extern bool   FLAG_mt;
 extern size_t FLAG_redzone;
 extern int    FLAG_debug;
 extern bool   FLAG_poison_shadow;
@@ -177,7 +176,6 @@
 
 // -------------------------- Atomic ---------------- {{{1
 static inline int AtomicInc(int *a) {
-  if (!FLAG_mt) return ++(*a);
 #ifdef ANDROID
   return __atomic_inc(a) + 1;
 #else
@@ -186,7 +184,6 @@
 }
 
 static inline int AtomicDec(int *a) {
-  if (!FLAG_mt) return --(*a);
 #ifdef ANDROID
   return __atomic_dec(a) - 1;
 #else
diff --git a/lib/asan/asan_rtl.cc b/lib/asan/asan_rtl.cc
index 71c4eb0..4fe840d 100644
--- a/lib/asan/asan_rtl.cc
+++ b/lib/asan/asan_rtl.cc
@@ -57,7 +57,6 @@
 bool   FLAG_fast_unwind = true;
 
 size_t FLAG_redzone;  // power of two, >= 32
-bool   FLAG_mt;  // set to 0 if you have only one thread.
 size_t FLAG_quarantine_size;
 int    FLAG_demangle;
 bool   FLAG_symbolize;
@@ -665,7 +664,6 @@
   FLAG_debug = IntFlagValue(options, "debug=", 0);
   FLAG_replace_cfallocator = IntFlagValue(options, "replace_cfallocator=", 1);
   FLAG_fast_unwind = IntFlagValue(options, "fast_unwind=", 1);
-  FLAG_mt = IntFlagValue(options, "mt=", 1);
   FLAG_replace_str = IntFlagValue(options, "replace_str=", 1);
   FLAG_replace_intrin = IntFlagValue(options, "replace_intrin=", 0);
   FLAG_use_fake_stack = IntFlagValue(options, "use_fake_stack=", 1);