diff --git a/Makefile b/Makefile
index a3df17e64..28548f7e9 100644
--- a/Makefile
+++ b/Makefile
@@ -40,8 +40,9 @@ endif
 #
 
 # keep standard at C11 and C++11
-OPT = -Ofast
-#OPT = -O3
+# -Ofast tends to produce faster code, but may not be available for some compilers.
+#OPT = -Ofast
+OPT = -O3
 CFLAGS   = -I.              $(OPT) -std=c11   -fPIC
 CXXFLAGS = -I. -I./examples $(OPT) -std=c++11 -fPIC
 LDFLAGS  =