diff --git a/lib/libgpio/Makefile b/lib/libgpio/Makefile
index b12822084..d93327518 100644
--- a/lib/libgpio/Makefile
+++ b/lib/libgpio/Makefile
@@ -1,6 +1,6 @@
-# Makefile for libmthread
+# Makefile for libgpio
 
-CPPFLAGS+= -O1 -Wall -Werror -D_SYSTEM
+CPPFLAGS+= -D_SYSTEM
 
 LIB=	gpio
 
diff --git a/lib/libmthread/Makefile b/lib/libmthread/Makefile
index c30afa63f..9861b7619 100644
--- a/lib/libmthread/Makefile
+++ b/lib/libmthread/Makefile
@@ -1,7 +1,5 @@
 # Makefile for libmthread
 
-CPPFLAGS+= -O1 -Wall -Werror
-
 LIB=	mthread
 
 SRCS=	\
diff --git a/lib/libpadconf/Makefile b/lib/libpadconf/Makefile
index c6d1e92b7..9aa95f5a4 100644
--- a/lib/libpadconf/Makefile
+++ b/lib/libpadconf/Makefile
@@ -1,6 +1,6 @@
 # Makefile for libpadconf
 
-CPPFLAGS+= -O1 -Wall -Werror -D_SYSTEM
+CPPFLAGS+= -D_SYSTEM
 
 LIB=	padconf
 
diff --git a/lib/librefuse/Makefile b/lib/librefuse/Makefile
index de640d259..5a6b9a485 100644
--- a/lib/librefuse/Makefile
+++ b/lib/librefuse/Makefile
@@ -6,7 +6,7 @@ LIB=		refuse
 LIBDPLIBS+=	puffs	${.CURDIR}/../libpuffs
 
 .ifdef DEBUG
-FUSE_OPT_DEBUG_FLAGS=	-g -DFUSE_OPT_DEBUG
+FUSE_OPT_DEBUG_FLAGS= -DFUSE_OPT_DEBUG
 .endif
 
 CFLAGS+=	${FUSE_OPT_DEBUG_FLAGS}
diff --git a/servers/inet/Makefile b/servers/inet/Makefile
index 6445e0398..ea43567ec 100644
--- a/servers/inet/Makefile
+++ b/servers/inet/Makefile
@@ -21,6 +21,6 @@ MAN=
 
 BINDIR?= /usr/sbin
 
-CPPFLAGS+=  -I${.CURDIR} -D'ARGS(a)=a' -Wall -Werror
+CPPFLAGS+=  -I${.CURDIR} -D'ARGS(a)=a'
 
 .include <minix.service.mk>
diff --git a/share/mk/sys.mk b/share/mk/sys.mk
index 6bb19769e..88a9ec20d 100644
--- a/share/mk/sys.mk
+++ b/share/mk/sys.mk
@@ -6,13 +6,12 @@ __MINIX=	yes
 
 .if defined(__MINIX)
 .if ${MKSMALL:U} == "yes"
+CPPFLAGS+= -DNDEBUG
 DBG=	-Os
-CFLAGS+= -DNDEBUG
 .endif
 
 unix?=		We run MINIX.
 
-DBG?=	-O
 CPP?=	/usr/lib/cpp
 .endif # defined(__MINIX)
 unix?=		We run NetBSD.