diff --git a/include/grpc/impl/codegen/grpc_types.h b/include/grpc/impl/codegen/grpc_types.h
index 4b3dff30404..33c160b4240 100644
--- a/include/grpc/impl/codegen/grpc_types.h
+++ b/include/grpc/impl/codegen/grpc_types.h
@@ -494,7 +494,8 @@ typedef struct grpc_event {
       field is guaranteed to be 0 */
   int success;
   /** The tag passed to grpc_call_start_batch etc to start this operation.
-      Only GRPC_OP_COMPLETE has a tag. */
+      *Only* GRPC_OP_COMPLETE has a tag. For all other grpc_completion_type
+      values, tag is uninitialized. */
   void* tag;
 } grpc_event;
 
diff --git a/src/core/lib/surface/call.cc b/src/core/lib/surface/call.cc
index 0b539b0d9b2..ff3df2605f3 100644
--- a/src/core/lib/surface/call.cc
+++ b/src/core/lib/surface/call.cc
@@ -1557,7 +1557,10 @@ static grpc_call_error call_start_batch(grpc_call* call, const grpc_op* ops,
           goto done_with_error;
         }
         /* process compression level */
-        memset(&call->compression_md, 0, sizeof(call->compression_md));
+        grpc_metadata& compression_md = call->compression_md;
+        compression_md.key = grpc_empty_slice();
+        compression_md.value = grpc_empty_slice();
+        compression_md.flags = 0;
         size_t additional_metadata_count = 0;
         grpc_compression_level effective_compression_level =
             GRPC_COMPRESS_LEVEL_NONE;
@@ -1580,8 +1583,8 @@ static grpc_call_error call_start_batch(grpc_call* call, const grpc_op* ops,
                   call, effective_compression_level);
           /* the following will be picked up by the compress filter and used
            * as the call's compression algorithm. */
-          call->compression_md.key = GRPC_MDSTR_GRPC_INTERNAL_ENCODING_REQUEST;
-          call->compression_md.value = grpc_compression_algorithm_slice(calgo);
+          compression_md.key = GRPC_MDSTR_GRPC_INTERNAL_ENCODING_REQUEST;
+          compression_md.value = grpc_compression_algorithm_slice(calgo);
           additional_metadata_count++;
         }
 
@@ -1595,8 +1598,7 @@ static grpc_call_error call_start_batch(grpc_call* call, const grpc_op* ops,
         if (!prepare_application_metadata(
                 call, static_cast<int>(op->data.send_initial_metadata.count),
                 op->data.send_initial_metadata.metadata, 0, call->is_client,
-                &call->compression_md,
-                static_cast<int>(additional_metadata_count))) {
+                &compression_md, static_cast<int>(additional_metadata_count))) {
           error = GRPC_CALL_ERROR_INVALID_METADATA;
           goto done_with_error;
         }
diff --git a/src/core/lib/surface/call_details.cc b/src/core/lib/surface/call_details.cc
index 7f20b1dae74..55e9e3425f2 100644
--- a/src/core/lib/surface/call_details.cc
+++ b/src/core/lib/surface/call_details.cc
@@ -29,7 +29,6 @@
 
 void grpc_call_details_init(grpc_call_details* cd) {
   GRPC_API_TRACE("grpc_call_details_init(cd=%p)", 1, (cd));
-  memset(cd, 0, sizeof(*cd));
   cd->method = grpc_empty_slice();
   cd->host = grpc_empty_slice();
 }
diff --git a/src/core/lib/surface/completion_queue.cc b/src/core/lib/surface/completion_queue.cc
index 7d679204bac..3a32d292a7b 100644
--- a/src/core/lib/surface/completion_queue.cc
+++ b/src/core/lib/surface/completion_queue.cc
@@ -1002,15 +1002,15 @@ static grpc_event cq_next(grpc_completion_queue* cq, gpr_timespec deadline,
         continue;
       }
 
-      memset(&ret, 0, sizeof(ret));
       ret.type = GRPC_QUEUE_SHUTDOWN;
+      ret.success = 0;
       break;
     }
 
     if (!is_finished_arg.first_loop &&
         grpc_core::ExecCtx::Get()->Now() >= deadline_millis) {
-      memset(&ret, 0, sizeof(ret));
       ret.type = GRPC_QUEUE_TIMEOUT;
+      ret.success = 0;
       dump_pending_tags(cq);
       break;
     }
@@ -1027,8 +1027,8 @@ static grpc_event cq_next(grpc_completion_queue* cq, gpr_timespec deadline,
       gpr_log(GPR_ERROR, "Completion queue next failed: %s", msg);
 
       GRPC_ERROR_UNREF(err);
-      memset(&ret, 0, sizeof(ret));
       ret.type = GRPC_QUEUE_TIMEOUT;
+      ret.success = 0;
       dump_pending_tags(cq);
       break;
     }
@@ -1234,8 +1234,8 @@ static grpc_event cq_pluck(grpc_completion_queue* cq, void* tag,
     }
     if (cqd->shutdown.Load(grpc_core::MemoryOrder::RELAXED)) {
       gpr_mu_unlock(cq->mu);
-      memset(&ret, 0, sizeof(ret));
       ret.type = GRPC_QUEUE_SHUTDOWN;
+      ret.success = 0;
       break;
     }
     if (!add_plucker(cq, tag, &worker)) {
@@ -1244,9 +1244,9 @@ static grpc_event cq_pluck(grpc_completion_queue* cq, void* tag,
               "is %d",
               GRPC_MAX_COMPLETION_QUEUE_PLUCKERS);
       gpr_mu_unlock(cq->mu);
-      memset(&ret, 0, sizeof(ret));
       /* TODO(ctiller): should we use a different result here */
       ret.type = GRPC_QUEUE_TIMEOUT;
+      ret.success = 0;
       dump_pending_tags(cq);
       break;
     }
@@ -1254,8 +1254,8 @@ static grpc_event cq_pluck(grpc_completion_queue* cq, void* tag,
         grpc_core::ExecCtx::Get()->Now() >= deadline_millis) {
       del_plucker(cq, tag, &worker);
       gpr_mu_unlock(cq->mu);
-      memset(&ret, 0, sizeof(ret));
       ret.type = GRPC_QUEUE_TIMEOUT;
+      ret.success = 0;
       dump_pending_tags(cq);
       break;
     }
@@ -1269,8 +1269,8 @@ static grpc_event cq_pluck(grpc_completion_queue* cq, void* tag,
       gpr_log(GPR_ERROR, "Completion queue pluck failed: %s", msg);
 
       GRPC_ERROR_UNREF(err);
-      memset(&ret, 0, sizeof(ret));
       ret.type = GRPC_QUEUE_TIMEOUT;
+      ret.success = 0;
       dump_pending_tags(cq);
       break;
     }
diff --git a/src/core/lib/surface/server.cc b/src/core/lib/surface/server.cc
index c6983ea9c95..c2b7e0436ef 100644
--- a/src/core/lib/surface/server.cc
+++ b/src/core/lib/surface/server.cc
@@ -347,8 +347,8 @@ static void channel_broadcaster_shutdown(channel_broadcaster* cb,
  */
 
 static void request_matcher_init(request_matcher* rm, grpc_server* server) {
-  memset(rm, 0, sizeof(*rm));
   rm->server = server;
+  rm->pending_head = rm->pending_tail = nullptr;
   rm->requests_per_cq = static_cast<gpr_locked_mpscq*>(
       gpr_malloc(sizeof(*rm->requests_per_cq) * server->cq_count));
   for (size_t i = 0; i < server->cq_count; i++) {
@@ -601,8 +601,9 @@ static void finish_start_new_rpc(
       break;
     case GRPC_SRM_PAYLOAD_READ_INITIAL_BYTE_BUFFER: {
       grpc_op op;
-      memset(&op, 0, sizeof(op));
       op.op = GRPC_OP_RECV_MESSAGE;
+      op.flags = 0;
+      op.reserved = nullptr;
       op.data.recv_message.recv_message = &calld->payload;
       GRPC_CLOSURE_INIT(&calld->publish, publish_new_rpc, elem,
                         grpc_schedule_on_exec_ctx);
diff --git a/src/csharp/Grpc.Core.Tests/Internal/CompletionQueueSafeHandleTest.cs b/src/csharp/Grpc.Core.Tests/Internal/CompletionQueueSafeHandleTest.cs
index 7e4e2975c16..a0ea1cc4278 100644
--- a/src/csharp/Grpc.Core.Tests/Internal/CompletionQueueSafeHandleTest.cs
+++ b/src/csharp/Grpc.Core.Tests/Internal/CompletionQueueSafeHandleTest.cs
@@ -47,7 +47,6 @@ namespace Grpc.Core.Internal.Tests
             GrpcEnvironment.ReleaseAsync().Wait();
             Assert.AreEqual(CompletionQueueEvent.CompletionType.Shutdown, ev.type);
             Assert.AreNotEqual(IntPtr.Zero, ev.success);
-            Assert.AreEqual(IntPtr.Zero, ev.tag);
         }
     }
 }
diff --git a/test/core/bad_connection/close_fd_test.cc b/test/core/bad_connection/close_fd_test.cc
index 317526a563a..e8f297e77ea 100644
--- a/test/core/bad_connection/close_fd_test.cc
+++ b/test/core/bad_connection/close_fd_test.cc
@@ -328,7 +328,6 @@ static void _test_close_before_server_recv(fd_type fdtype) {
    */
   if (event.type == GRPC_QUEUE_TIMEOUT) {
     GPR_ASSERT(event.success == 0);
-    GPR_ASSERT(event.tag == nullptr);
     /* status is not initialized */
     GPR_ASSERT(status == GRPC_STATUS__DO_NOT_USE);
   } else {
@@ -531,7 +530,6 @@ static void _test_close_before_server_send(fd_type fdtype) {
   } else {
     GPR_ASSERT(event.type == GRPC_QUEUE_TIMEOUT);
     GPR_ASSERT(event.success == 0);
-    GPR_ASSERT(event.tag == nullptr);
     /* status is not initialized */
     GPR_ASSERT(status == GRPC_STATUS__DO_NOT_USE);
   }
@@ -664,7 +662,6 @@ static void _test_close_before_client_send(fd_type fdtype) {
       g_ctx.cq, grpc_timeout_milliseconds_to_deadline(100), nullptr);
   GPR_ASSERT(event.success == 0);
   GPR_ASSERT(event.type == GRPC_QUEUE_TIMEOUT);
-  GPR_ASSERT(event.tag == nullptr);
 
   grpc_slice_unref(details);
   grpc_metadata_array_destroy(&initial_metadata_recv);
@@ -720,13 +717,11 @@ static void _test_close_before_call_create(fd_type fdtype) {
       g_ctx.client_cq, grpc_timeout_milliseconds_to_deadline(100), nullptr);
   GPR_ASSERT(event.type == GRPC_QUEUE_TIMEOUT);
   GPR_ASSERT(event.success == 0);
-  GPR_ASSERT(event.tag == nullptr);
 
   event = grpc_completion_queue_next(
       g_ctx.cq, grpc_timeout_milliseconds_to_deadline(100), nullptr);
   GPR_ASSERT(event.type == GRPC_QUEUE_TIMEOUT);
   GPR_ASSERT(event.success == 0);
-  GPR_ASSERT(event.tag == nullptr);
 
   grpc_call_unref(call);
   end_test();