diff --git a/src/utils/wpabuf.c b/src/utils/wpabuf.c
index 3719aaeed..e809690b9 100644
--- a/src/utils/wpabuf.c
+++ b/src/utils/wpabuf.c
@@ -160,3 +160,38 @@ struct wpabuf * wpabuf_concat(struct wpabuf *a, struct wpabuf *b)
 
 	return n;
 }
+
+
+/**
+ * wpabuf_zeropad - Pad buffer with 0x00 octets (prefix) to specified length
+ * @buf: Buffer to be padded
+ * @len: Length for the padded buffer
+ * Returns: wpabuf padded to len octets or %NULL on failure
+ *
+ * If buf is longer than len octets or of same size, it will be returned as-is.
+ * Otherwise a new buffer is allocated and prefixed with 0x00 octets followed
+ * by the source data. The source buffer will be freed on error, i.e., caller
+ * will only be responsible on freeing the returned buffer. If buf is %NULL,
+ * %NULL will be returned.
+ */
+struct wpabuf * wpabuf_zeropad(struct wpabuf *buf, size_t len)
+{
+	struct wpabuf *ret;
+	size_t blen;
+
+	if (buf == NULL)
+		return NULL;
+
+	blen = wpabuf_len(buf);
+	if (blen >= len)
+		return buf;
+
+	ret = wpabuf_alloc(len);
+	if (ret) {
+		os_memset(wpabuf_put(ret, len - blen), 0, len - blen);
+		wpabuf_put_buf(ret, buf);
+	}
+	wpabuf_free(buf);
+
+	return ret;
+}
diff --git a/src/utils/wpabuf.h b/src/utils/wpabuf.h
index 724412e31..5d435ab10 100644
--- a/src/utils/wpabuf.h
+++ b/src/utils/wpabuf.h
@@ -37,6 +37,7 @@ struct wpabuf * wpabuf_dup(const struct wpabuf *src);
 void wpabuf_free(struct wpabuf *buf);
 void * wpabuf_put(struct wpabuf *buf, size_t len);
 struct wpabuf * wpabuf_concat(struct wpabuf *a, struct wpabuf *b);
+struct wpabuf * wpabuf_zeropad(struct wpabuf *buf, size_t len);
 
 
 /**
diff --git a/src/wps/wps_attr_build.c b/src/wps/wps_attr_build.c
index c30e17b3d..edeff5c58 100644
--- a/src/wps/wps_attr_build.c
+++ b/src/wps/wps_attr_build.c
@@ -27,6 +27,7 @@ int wps_build_public_key(struct wps_data *wps, struct wpabuf *msg)
 
 	wpa_printf(MSG_DEBUG, "WPS:  * Public Key");
 	pubkey = dh_init(dh_groups_get(WPS_DH_GROUP), &wps->dh_privkey);
+	pubkey = wpabuf_zeropad(pubkey, 192);
 	if (pubkey == NULL) {
 		wpa_printf(MSG_DEBUG, "WPS: Failed to initialize "
 			   "Diffie-Hellman handshake");
diff --git a/src/wps/wps_common.c b/src/wps/wps_common.c
index 9273d3749..050f04305 100644
--- a/src/wps/wps_common.c
+++ b/src/wps/wps_common.c
@@ -82,6 +82,7 @@ int wps_derive_keys(struct wps_data *wps)
 
 	dh_shared = dh_derive_shared(pubkey, wps->dh_privkey,
 				     dh_groups_get(WPS_DH_GROUP));
+	dh_shared = wpabuf_zeropad(dh_shared, 192);
 	if (dh_shared == NULL) {
 		wpa_printf(MSG_DEBUG, "WPS: Failed to derive DH shared key");
 		return -1;