diff --git a/ip2net/Makefile b/ip2net/Makefile
index 97a53d7..56f6b17 100644
--- a/ip2net/Makefile
+++ b/ip2net/Makefile
@@ -1,5 +1,5 @@
 CC ?= gcc
-CFLAGS += -std=gnu99 -O3
+CFLAGS += -std=gnu99 -Os
 CFLAGS_BSD = -Wno-address-of-packed-member
 CFLAGS_WIN = -static
 LIBS = 
diff --git a/mdig/Makefile b/mdig/Makefile
index 58bc4b4..0100b5b 100644
--- a/mdig/Makefile
+++ b/mdig/Makefile
@@ -1,5 +1,5 @@
 CC ?= gcc
-CFLAGS += -std=gnu99 -O3
+CFLAGS += -std=gnu99 -Os
 CFLAGS_BSD = -Wno-address-of-packed-member
 CFLAGS_WIN = -static
 LIBS = -lpthread
diff --git a/nfq/BSDmakefile b/nfq/BSDmakefile
index 1717340..ff5475e 100644
--- a/nfq/BSDmakefile
+++ b/nfq/BSDmakefile
@@ -1,5 +1,5 @@
 CC ?= cc
-CFLAGS += -std=gnu99 -s -O3 -Wno-address-of-packed-member
+CFLAGS += -std=gnu99 -s -Os -Wno-address-of-packed-member
 LIBS = -lz
 SRC_FILES = *.c crypto/*.c
 
diff --git a/nfq/Makefile b/nfq/Makefile
index fb8c900..e2a1779 100644
--- a/nfq/Makefile
+++ b/nfq/Makefile
@@ -1,5 +1,5 @@
 CC ?= gcc
-CFLAGS += -std=gnu99 -O3
+CFLAGS += -std=gnu99 -Os
 CFLAGS_BSD = -Wno-address-of-packed-member
 CFLAGS_MAC = -mmacosx-version-min=10.8
 CFLAGS_CYGWIN = -Wno-address-of-packed-member -static
diff --git a/tpws/BSDmakefile b/tpws/BSDmakefile
index 568f67b..e9ad901 100644
--- a/tpws/BSDmakefile
+++ b/tpws/BSDmakefile
@@ -1,5 +1,5 @@
 CC ?= cc
-CFLAGS += -std=gnu99 -s -O3
+CFLAGS += -std=gnu99 -s -Os
 LIBS = -lz -lpthread
 SRC_FILES = *.c
 
diff --git a/tpws/Makefile b/tpws/Makefile
index 52b72f7..b2b00ea 100644
--- a/tpws/Makefile
+++ b/tpws/Makefile
@@ -1,5 +1,5 @@
 CC ?= gcc
-CFLAGS += -std=gnu99 -O3
+CFLAGS += -std=gnu99 -Os
 CFLAGS_BSD = -Wno-address-of-packed-member
 LIBS = -lz -lpthread
 SRC_FILES = *.c