diff --git a/test/encode_api_test.cc b/test/encode_api_test.cc
index e2374abb4bd..0aa8739d6a3 100644
--- a/test/encode_api_test.cc
+++ b/test/encode_api_test.cc
@@ -801,6 +801,25 @@ TEST(EncodeAPI, Buganizer311394513) {
   encoder.Encode(true);
 }
 
+TEST(EncodeAPI, Buganizer311985118) {
+  VP9Encoder encoder(0);
+
+  // Set initial config, in particular set deadline to GOOD mode.
+  encoder.Configure(12, 1678, 620, VPX_VBR, VPX_DL_GOOD_QUALITY);
+
+  // Encode 1st frame.
+  encoder.Encode(false);
+
+  // Change config: change threads and width.
+  encoder.Configure(0, 1574, 620, VPX_VBR, VPX_DL_GOOD_QUALITY);
+
+  // Change config: change threads, width and height.
+  encoder.Configure(16, 837, 432, VPX_VBR, VPX_DL_GOOD_QUALITY);
+
+  // Encode 2nd frame.
+  encoder.Encode(false);
+}
+
 // This is a test case from clusterfuzz: based on b/314857577.
 // Encode a few frames with multiple change config calls
 // with different frame sizes.
diff --git a/vp9/encoder/vp9_encoder.c b/vp9/encoder/vp9_encoder.c
index 20e35077cd4..152d42bc9a6 100644
--- a/vp9/encoder/vp9_encoder.c
+++ b/vp9/encoder/vp9_encoder.c
@@ -3888,6 +3888,7 @@ static void set_frame_size(VP9_COMP *cpi) {
   alloc_util_frame_buffers(cpi);
   init_motion_estimation(cpi);
 
+  int has_valid_ref_frame = 0;
   for (ref_frame = LAST_FRAME; ref_frame <= ALTREF_FRAME; ++ref_frame) {
     RefBuffer *const ref_buf = &cm->frame_refs[ref_frame - 1];
     const int buf_idx = get_ref_frame_buf_idx(cpi, ref_frame);
@@ -3906,11 +3907,17 @@ static void set_frame_size(VP9_COMP *cpi) {
                                         buf->y_crop_height, cm->width,
                                         cm->height);
 #endif  // CONFIG_VP9_HIGHBITDEPTH
+      has_valid_ref_frame |= vp9_is_valid_scale(&ref_buf->sf);
       if (vp9_is_scaled(&ref_buf->sf)) vpx_extend_frame_borders(buf);
     } else {
       ref_buf->buf = NULL;
     }
   }
+  if (!frame_is_intra_only(cm) && !has_valid_ref_frame) {
+    vpx_internal_error(
+        &cm->error, VPX_CODEC_CORRUPT_FRAME,
+        "Can't find at least one reference frame with valid size");
+  }
 
   set_ref_ptrs(cm, xd, LAST_FRAME, LAST_FRAME);
 }
diff --git a/vp9/encoder/vp9_encoder.h b/vp9/encoder/vp9_encoder.h
index 83b7081e7bc..7136f7faa34 100644
--- a/vp9/encoder/vp9_encoder.h
+++ b/vp9/encoder/vp9_encoder.h
@@ -921,6 +921,9 @@ typedef struct VP9_COMP {
                     // number of MBs in the current frame when the frame is
                     // scaled.
 
+  int last_coded_width;
+  int last_coded_height;
+
   int use_svc;
 
   SVC svc;
diff --git a/vp9/vp9_cx_iface.c b/vp9/vp9_cx_iface.c
index b75fc18fd27..d4c41d16f38 100644
--- a/vp9/vp9_cx_iface.c
+++ b/vp9/vp9_cx_iface.c
@@ -797,10 +797,22 @@ static vpx_codec_err_t encoder_set_config(vpx_codec_alg_priv_t *ctx,
   if (cfg->g_w != ctx->cfg.g_w || cfg->g_h != ctx->cfg.g_h) {
     if (cfg->g_lag_in_frames > 1 || cfg->g_pass != VPX_RC_ONE_PASS)
       ERROR("Cannot change width or height after initialization");
-    if (!valid_ref_frame_size(ctx->cfg.g_w, ctx->cfg.g_h, cfg->g_w, cfg->g_h) ||
+    // Note: function encoder_set_config() is allowed to be called multiple
+    // times. However, when the original frame width or height is less than two
+    // times of the new frame width or height, a forced key frame should be
+    // used. To make sure the correct detection of a forced key frame, we need
+    // to update the frame width and height only when the actual encoding is
+    // performed. cpi->last_coded_width and cpi->last_coded_height are used to
+    // track the actual coded frame size.
+    if ((ctx->cpi->last_coded_width && ctx->cpi->last_coded_height &&
+         !valid_ref_frame_size(ctx->cpi->last_coded_width,
+                               ctx->cpi->last_coded_height, cfg->g_w,
+                               cfg->g_h)) ||
         (ctx->cpi->initial_width && (int)cfg->g_w > ctx->cpi->initial_width) ||
-        (ctx->cpi->initial_height && (int)cfg->g_h > ctx->cpi->initial_height))
+        (ctx->cpi->initial_height &&
+         (int)cfg->g_h > ctx->cpi->initial_height)) {
       force_key = 1;
+    }
   }
 
   // Prevent increasing lag_in_frames. This check is stricter than it needs
@@ -1310,6 +1322,9 @@ static vpx_codec_err_t encoder_encode(vpx_codec_alg_priv_t *ctx,
 
   if (cpi == NULL) return VPX_CODEC_INVALID_PARAM;
 
+  cpi->last_coded_width = ctx->oxcf.width;
+  cpi->last_coded_height = ctx->oxcf.height;
+
   if (img != NULL) {
     res = validate_img(ctx, img);
     if (res == VPX_CODEC_OK) {