diff --git a/lib/nghttp2_session.c b/lib/nghttp2_session.c
index 97cdd1ba..f390621d 100644
--- a/lib/nghttp2_session.c
+++ b/lib/nghttp2_session.c
@@ -4684,12 +4684,8 @@ ssize_t nghttp2_session_mem_recv(nghttp2_session *session, const uint8_t *in,
 
       if (iframe->sbuf.pos[3] != NGHTTP2_SETTINGS ||
           (iframe->sbuf.pos[4] & NGHTTP2_FLAG_ACK)) {
-        nghttp2_frame_unpack_frame_hd(&iframe->frame.hd, iframe->sbuf.pos);
-        iframe->payloadleft = iframe->frame.hd.length;
 
-        busy = 1;
-
-        iframe->state = NGHTTP2_IB_IGN_PAYLOAD;
+        iframe->state = NGHTTP2_IB_IGN_ALL;
 
         rv = nghttp2_session_terminate_session_with_reason(
             session, NGHTTP2_PROTOCOL_ERROR, "SETTINGS expected");
@@ -4698,7 +4694,7 @@ ssize_t nghttp2_session_mem_recv(nghttp2_session *session, const uint8_t *in,
           return rv;
         }
 
-        break;
+        return inlen;
       }
 
       iframe->state = NGHTTP2_IB_READ_HEAD;
@@ -5649,6 +5645,8 @@ ssize_t nghttp2_session_mem_recv(nghttp2_session *session, const uint8_t *in,
       session_inbound_frame_reset(session);
 
       break;
+    case NGHTTP2_IB_IGN_ALL:
+      return inlen;
     }
 
     if (!busy && in == last) {
diff --git a/lib/nghttp2_session.h b/lib/nghttp2_session.h
index 651a36ff..c9422a5d 100644
--- a/lib/nghttp2_session.h
+++ b/lib/nghttp2_session.h
@@ -81,7 +81,8 @@ typedef enum {
   NGHTTP2_IB_IGN_CONTINUATION,
   NGHTTP2_IB_READ_PAD_DATA,
   NGHTTP2_IB_READ_DATA,
-  NGHTTP2_IB_IGN_DATA
+  NGHTTP2_IB_IGN_DATA,
+  NGHTTP2_IB_IGN_ALL,
 } nghttp2_inbound_state;
 
 #define NGHTTP2_INBOUND_NUM_IV 7
diff --git a/tests/nghttp2_session_test.c b/tests/nghttp2_session_test.c
index 09f98a70..be6016d6 100644
--- a/tests/nghttp2_session_test.c
+++ b/tests/nghttp2_session_test.c
@@ -6581,15 +6581,15 @@ void test_nghttp2_session_recv_client_preface(void) {
   CU_ASSERT(rv == NGHTTP2_CLIENT_CONNECTION_PREFACE_LEN);
   CU_ASSERT(NGHTTP2_IB_READ_FIRST_SETTINGS == session->iframe.state);
 
-  /* Receiving PING is error */
+  /* Receiving PING is error because we want SETTINGS. */
   nghttp2_frame_ping_init(&ping_frame.ping, NGHTTP2_FLAG_NONE, NULL);
 
   nghttp2_frame_pack_frame_hd(buf, &ping_frame.ping.hd);
 
   rv = nghttp2_session_mem_recv(session, buf, NGHTTP2_FRAME_HDLEN);
   CU_ASSERT(NGHTTP2_FRAME_HDLEN == rv);
-  CU_ASSERT(NGHTTP2_IB_IGN_PAYLOAD == session->iframe.state);
-  CU_ASSERT(8 == session->iframe.payloadleft);
+  CU_ASSERT(NGHTTP2_IB_IGN_ALL == session->iframe.state);
+  CU_ASSERT(0 == session->iframe.payloadleft);
 
   nghttp2_frame_ping_free(&ping_frame.ping);