diff --git a/src/backend.c b/src/backend.c
index 69b6345c6..59458e5e8 100644
--- a/src/backend.c
+++ b/src/backend.c
@@ -4491,6 +4491,7 @@ int gidd_to_pw_t (hashcat_ctx_t *hashcat_ctx, hc_device_param_t *device_param, c
 
   if (device_param->is_opencl == true)
   {
+    /* blocking */
     if (hc_clEnqueueReadBuffer (hashcat_ctx, device_param->opencl_command_queue, device_param->opencl_d_pws_idx, CL_TRUE, gidd * sizeof (pw_idx_t), sizeof (pw_idx_t), &pw_idx, 0, NULL, NULL) == -1) return -1;
   }
 
@@ -4530,6 +4531,7 @@ int gidd_to_pw_t (hashcat_ctx_t *hashcat_ctx, hc_device_param_t *device_param, c
   {
     if (cnt > 0)
     {
+      /* blocking */
       if (hc_clEnqueueReadBuffer (hashcat_ctx, device_param->opencl_command_queue, device_param->opencl_d_pws_comp_buf, CL_TRUE, off * sizeof (u32), cnt * sizeof (u32), pw->i, 0, NULL, NULL) == -1) return -1;
     }
   }
diff --git a/src/hashes.c b/src/hashes.c
index e1f8402c2..9145c9834 100644
--- a/src/hashes.c
+++ b/src/hashes.c
@@ -574,6 +574,7 @@ int check_cracked (hashcat_ctx_t *hashcat_ctx, hc_device_param_t *device_param)
 
   if (device_param->is_opencl == true)
   {
+    /* blocking */
     if (hc_clEnqueueReadBuffer (hashcat_ctx, device_param->opencl_command_queue, device_param->opencl_d_result, CL_TRUE, 0, sizeof (u32), &num_cracked, 0, NULL, NULL) == -1) return -1;
   }
 
@@ -623,6 +624,7 @@ int check_cracked (hashcat_ctx_t *hashcat_ctx, hc_device_param_t *device_param)
 
   if (device_param->is_opencl == true)
   {
+    /* blocking */
     rc = hc_clEnqueueReadBuffer (hashcat_ctx, device_param->opencl_command_queue, device_param->opencl_d_plain_bufs, CL_TRUE, 0, num_cracked * sizeof (plain_t), cracked, 0, NULL, NULL);
 
     if (rc == -1)
diff --git a/src/selftest.c b/src/selftest.c
index d5fff9433..af3a94550 100644
--- a/src/selftest.c
+++ b/src/selftest.c
@@ -523,6 +523,7 @@ static int selftest (hashcat_ctx_t *hashcat_ctx, hc_device_param_t *device_param
 
       if (device_param->is_opencl == true)
       {
+        /* blocking */
         if (hc_clEnqueueReadBuffer (hashcat_ctx, device_param->opencl_command_queue, device_param->opencl_d_hooks, CL_TRUE, 0, device_param->size_hooks, device_param->hooks_buf, 0, NULL, NULL) == -1) return -1;
       }
 
@@ -600,6 +601,7 @@ static int selftest (hashcat_ctx_t *hashcat_ctx, hc_device_param_t *device_param
 
         if (device_param->is_opencl == true)
         {
+          /* blocking */
           if (hc_clEnqueueReadBuffer (hashcat_ctx, device_param->opencl_command_queue, device_param->opencl_d_hooks, CL_TRUE, 0, device_param->size_hooks, device_param->hooks_buf, 0, NULL, NULL) == -1) return -1;
         }