diff --git a/src/core/surface/event_string.c b/src/core/surface/event_string.c
index e38ef06c9ff..5a71cdadaba 100644
--- a/src/core/surface/event_string.c
+++ b/src/core/surface/event_string.c
@@ -38,8 +38,10 @@
 #include "src/core/support/string.h"
 #include <grpc/byte_buffer.h>
 
-static size_t addhdr(char *p, grpc_event *ev) {
-  return sprintf(p, "tag:%p call:%p", ev->tag, (void *)ev->call);
+static void addhdr(gpr_strvec *buf, grpc_event *ev) {
+  char *tmp;
+  gpr_asprintf(&tmp, "tag:%p call:%p", ev->tag, (void *)ev->call);
+  gpr_strvec_add(buf, tmp);
 }
 
 static const char *errstr(grpc_op_error err) {
@@ -52,72 +54,84 @@ static const char *errstr(grpc_op_error err) {
   return "UNKNOWN_UNKNOWN";
 }
 
-static size_t adderr(char *p, grpc_op_error err) {
-  return sprintf(p, " err=%s", errstr(err));
+static void adderr(gpr_strvec *buf, grpc_op_error err) {
+  char *tmp;
+  gpr_asprintf(&tmp, " err=%s", errstr(err));
+  gpr_strvec_add(buf, tmp);
 }
 
 char *grpc_event_string(grpc_event *ev) {
-  char buffer[1024];
-  char *p = buffer;
+  char *out;
+  char *tmp;
+  gpr_strvec buf;
 
   if (ev == NULL) return gpr_strdup("null");
 
+  gpr_strvec_init(&buf);
+
   switch (ev->type) {
     case GRPC_SERVER_SHUTDOWN:
-      p += sprintf(p, "SERVER_SHUTDOWN");
+      gpr_strvec_add(&buf, gpr_strdup("SERVER_SHUTDOWN"));
       break;
     case GRPC_QUEUE_SHUTDOWN:
-      p += sprintf(p, "QUEUE_SHUTDOWN");
+      gpr_strvec_add(&buf, gpr_strdup("QUEUE_SHUTDOWN"));
       break;
     case GRPC_READ:
-      p += sprintf(p, "READ: ");
-      p += addhdr(p, ev);
+      gpr_strvec_add(&buf, gpr_strdup("READ: "));
+      addhdr(&buf, ev);
       if (ev->data.read) {
-        p += sprintf(p, " %d bytes",
+        gpr_asprintf(&tmp, " %d bytes",
                      (int)grpc_byte_buffer_length(ev->data.read));
+        gpr_strvec_add(&buf, tmp);
       } else {
-        p += sprintf(p, " end-of-stream");
+        gpr_strvec_add(&buf, gpr_strdup(" end-of-stream"));
       }
       break;
     case GRPC_INVOKE_ACCEPTED:
-      p += sprintf(p, "INVOKE_ACCEPTED: ");
-      p += addhdr(p, ev);
-      p += adderr(p, ev->data.invoke_accepted);
+      gpr_strvec_add(&buf, gpr_strdup("INVOKE_ACCEPTED: "));
+      addhdr(&buf, ev);
+      adderr(&buf, ev->data.invoke_accepted);
       break;
     case GRPC_WRITE_ACCEPTED:
-      p += sprintf(p, "WRITE_ACCEPTED: ");
-      p += addhdr(p, ev);
-      p += adderr(p, ev->data.write_accepted);
+      gpr_strvec_add(&buf, gpr_strdup("WRITE_ACCEPTED: "));
+      addhdr(&buf, ev);
+      adderr(&buf, ev->data.write_accepted);
       break;
     case GRPC_FINISH_ACCEPTED:
-      p += sprintf(p, "FINISH_ACCEPTED: ");
-      p += addhdr(p, ev);
-      p += adderr(p, ev->data.write_accepted);
+      gpr_strvec_add(&buf, gpr_strdup("FINISH_ACCEPTED: "));
+      addhdr(&buf, ev);
+      adderr(&buf, ev->data.write_accepted);
       break;
     case GRPC_CLIENT_METADATA_READ:
-      p += sprintf(p, "CLIENT_METADATA_READ: ");
-      p += addhdr(p, ev);
-      p += sprintf(p, " %d elements", (int)ev->data.client_metadata_read.count);
+      gpr_strvec_add(&buf, gpr_strdup("CLIENT_METADATA_READ: "));
+      addhdr(&buf, ev);
+      gpr_asprintf(&tmp, " %d elements",
+                   (int)ev->data.client_metadata_read.count);
+      gpr_strvec_add(&buf, tmp);
       break;
     case GRPC_FINISHED:
-      p += sprintf(p, "FINISHED: ");
-      p += addhdr(p, ev);
-      p += sprintf(p, " status=%d details='%s' %d metadata elements",
+      gpr_strvec_add(&buf, gpr_strdup("FINISHED: "));
+      addhdr(&buf, ev);
+      gpr_asprintf(&tmp, " status=%d details='%s' %d metadata elements",
                    ev->data.finished.status, ev->data.finished.details,
                    (int)ev->data.finished.metadata_count);
+      gpr_strvec_add(&buf, tmp);
       break;
     case GRPC_SERVER_RPC_NEW:
-      p += sprintf(p, "SERVER_RPC_NEW: ");
-      p += addhdr(p, ev);
-      p += sprintf(p, " method='%s' host='%s' %d metadata elements",
+      gpr_strvec_add(&buf, gpr_strdup("SERVER_RPC_NEW: "));
+      addhdr(&buf, ev);
+      gpr_asprintf(&tmp, " method='%s' host='%s' %d metadata elements",
                    ev->data.server_rpc_new.method, ev->data.server_rpc_new.host,
                    (int)ev->data.server_rpc_new.metadata_count);
+      gpr_strvec_add(&buf, tmp);
       break;
     case GRPC_COMPLETION_DO_NOT_USE:
-      p += sprintf(p, "DO_NOT_USE (this is a bug)");
-      p += addhdr(p, ev);
+      gpr_strvec_add(&buf, gpr_strdup("DO_NOT_USE (this is a bug)"));
+      addhdr(&buf, ev);
       break;
   }
 
-  return gpr_strdup(buffer);
+  out = gpr_strvec_flatten(&buf);
+  gpr_strvec_destroy(&buf);
+  return out;
 }