diff --git a/libnetutils/Android.mk b/libnetutils/Android.mk
index aba4621..1f61511 100644
--- a/libnetutils/Android.mk
+++ b/libnetutils/Android.mk
@@ -1,7 +1,7 @@
-LOCAL_PATH:= $(call my-dir)
+LOCAL_PATH := $(call my-dir)
 include $(CLEAR_VARS)
 
-LOCAL_SRC_FILES:= \
+LOCAL_SRC_FILES := \
         dhcpclient.c \
         dhcpmsg.c \
         dhcp_utils.c \
@@ -12,6 +12,8 @@
         libcutils \
         liblog
 
-LOCAL_MODULE:= libnetutils
+LOCAL_MODULE := libnetutils
+
+LOCAL_CFLAGS := -Werror
 
 include $(BUILD_SHARED_LIBRARY)
diff --git a/libnetutils/dhcpclient.c b/libnetutils/dhcpclient.c
index 34500e7..b58120e 100644
--- a/libnetutils/dhcpclient.c
+++ b/libnetutils/dhcpclient.c
@@ -282,16 +282,18 @@
     ALOGD("chaddr = {%s}", buf);
 
     for (n = 0; n < 64; n++) {
-        if ((msg->sname[n] < ' ') || (msg->sname[n] > 127)) {
-            if (msg->sname[n] == 0) break;
+        unsigned char x = msg->sname[n];
+        if ((x < ' ') || (x > 127)) {
+            if (x == 0) break;
             msg->sname[n] = '.';
         }
     }
     msg->sname[63] = 0;
 
     for (n = 0; n < 128; n++) {
-        if ((msg->file[n] < ' ') || (msg->file[n] > 127)) {
-            if (msg->file[n] == 0) break;
+        unsigned char x = msg->file[n];
+        if ((x < ' ') || (x > 127)) {
+            if (x == 0) break;
             msg->file[n] = '.';
         }
     }