diff --git a/.github/workflows/ci-large.yml b/.github/workflows/ci-large.yml
index 793993b18..87aef14ce 100644
--- a/.github/workflows/ci-large.yml
+++ b/.github/workflows/ci-large.yml
@@ -113,7 +113,7 @@ jobs:
         wasmer: [3.1.1]
         v8: [12.0.267.17]
         ssl: [no_ssl, ssl]
-        debug: [debug, no_debug]
+        debug: [debug]
     uses: ./.github/workflows/job-clang-analyzer.yml
     with:
       cc: ${{ matrix.cc }}
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index bfb9f0e36..4bfeb4ac0 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -261,7 +261,7 @@ jobs:
         wasmer: [3.1.1]
         v8: [12.0.267.17]
         ssl: [ssl]
-        debug: [debug, no_debug]
+        debug: [debug]
         include:
           # No SSL
           - os: ubuntu-latest
diff --git a/src/common/proxy_wasm/ngx_proxy_wasm_host.c b/src/common/proxy_wasm/ngx_proxy_wasm_host.c
index 591dd9f0a..76a5c5b95 100644
--- a/src/common/proxy_wasm/ngx_proxy_wasm_host.c
+++ b/src/common/proxy_wasm/ngx_proxy_wasm_host.c
@@ -373,7 +373,7 @@ ngx_proxy_wasm_hfuncs_get_buffer(ngx_wavm_instance_t *instance,
     if (start == NULL) {
         ngx_wa_assert(cl);
 
-        if (cl->next == NULL) {
+        if (cl && cl->next == NULL) {
             /* single buffer */
             start = cl->buf->pos;
         }
@@ -388,6 +388,7 @@ ngx_proxy_wasm_hfuncs_get_buffer(ngx_wavm_instance_t *instance,
         ngx_wa_assert(cl);
         ngx_wa_assert(cl->buf);
         ngx_wa_assert(cl->next);
+
         len = 0;
 
         for (/* void */; cl; cl = cl->next) {
diff --git a/src/common/shm/ngx_wasm_shm_queue.c b/src/common/shm/ngx_wasm_shm_queue.c
index 2b90f8563..55093602e 100644
--- a/src/common/shm/ngx_wasm_shm_queue.c
+++ b/src/common/shm/ngx_wasm_shm_queue.c
@@ -216,8 +216,12 @@ ngx_wasm_shm_queue_pop_locked(ngx_wasm_shm_t *shm, ngx_str_t *data_out,
     }
 
     inc_ptr(queue, &queue->pop_ptr, sizeof(uint32_t));
+
+    ngx_wa_assert(buf);
+
     circular_read(shm->log, queue, queue->pop_ptr, buf, len);
     inc_ptr(queue, &queue->pop_ptr, len);
+
     queue->rising_occupancy = 0;
 
     data_out->data = buf;
diff --git a/src/wasm/ngx_wasm_util.c b/src/wasm/ngx_wasm_util.c
index 5c67d5746..4731d38de 100644
--- a/src/wasm/ngx_wasm_util.c
+++ b/src/wasm/ngx_wasm_util.c
@@ -105,7 +105,9 @@ ngx_wasm_chain_clear(ngx_chain_t *in, size_t offset, unsigned *eof,
 
     if (pos < offset) {
         fill = offset - pos;
+#if (NGX_DEBUG)
         pos += fill;
+#endif
     }
 
     ngx_wa_assert(pos == offset);