diff --git a/build/defaults.mak b/build/defaults.mak
index 2b3d8f085..628550f3d 100644
--- a/build/defaults.mak
+++ b/build/defaults.mak
@@ -18,6 +18,11 @@ else
 SFLAGS += -Os
 endif
 
+ifeq ($(ASAN),1)
+SFLAGS += -fsanitize=address
+LDFLAGS += -fsanitize=address
+endif
+
 # Flags - Header search path
 SFLAGS += -Ilib -I.
 
diff --git a/build/toolchain.afl.mak b/build/toolchain.afl.mak
index a3e56d9be..28fa52426 100644
--- a/build/toolchain.afl.mak
+++ b/build/toolchain.afl.mak
@@ -2,3 +2,7 @@ export AFL_QUIET = 1
 CC = afl-clang
 CXX = afl-clang++
 LD = afl-clang++
+
+ifeq ($(ASAN),1)
+export AFL_USE_ASAN = 1
+endif