diff --git a/src/p2p/p2p_parse.c b/src/p2p/p2p_parse.c
index 44b0098..def41ff 100644
--- a/src/p2p/p2p_parse.c
+++ b/src/p2p/p2p_parse.c
@@ -161,8 +161,7 @@
 		for (i = 0; i < nlen; i++) {
 			if (msg->device_name[i] == '\0')
 				break;
-			if (msg->device_name[i] > 0 &&
-			    msg->device_name[i] < 32)
+			if (is_ctrl_char(msg->device_name[i]))
 				msg->device_name[i] = '_';
 		}
 		wpa_printf(MSG_DEBUG, "P2P: * Device Info: addr " MACSTR
@@ -743,7 +742,7 @@
 		name[cli->dev_name_len] = '\0';
 		count = (int) cli->dev_name_len - 1;
 		while (count >= 0) {
-			if (name[count] > 0 && name[count] < 32)
+			if (is_ctrl_char(name[count]))
 				name[count] = '_';
 			count--;
 		}
diff --git a/src/utils/common.c b/src/utils/common.c
index c31717c..5cf0d57 100644
--- a/src/utils/common.c
+++ b/src/utils/common.c
@@ -1088,3 +1088,9 @@
 
 	return res_size;
 }
+
+
+int is_ctrl_char(char c)
+{
+	return c > 0 && c < 32;
+}
diff --git a/src/utils/common.h b/src/utils/common.h
index a0eda4a..88318f5 100644
--- a/src/utils/common.h
+++ b/src/utils/common.h
@@ -554,6 +554,7 @@
 		   char *outp, size_t out_size);
 size_t utf8_unescape(const char *inp, size_t in_size,
 		     char *outp, size_t out_size);
+int is_ctrl_char(char c);
 
 
 /*
diff --git a/src/wps/wps.c b/src/wps/wps.c
index 2c68be8..498f11f 100644
--- a/src/wps/wps.c
+++ b/src/wps/wps.c
@@ -618,7 +618,8 @@
 		if (str == NULL)
 			return pos - buf;
 		for (i = 0; i < attr.dev_name_len; i++) {
-			if (attr.dev_name[i] < 32)
+			if (attr.dev_name[i] == 0 ||
+			    is_ctrl_char(attr.dev_name[i]))
 				str[i] = '_';
 			else
 				str[i] = attr.dev_name[i];