diff --git a/src/x11.cc b/src/x11.cc
index cb77b1887..b1040fb21 100644
--- a/src/x11.cc
+++ b/src/x11.cc
@@ -246,7 +246,7 @@ static int x11_error_handler(Display *d, XErrorEvent *err) {
         xcb_errors_ctx, err->error_code, &extension);
     if (extension != nullptr) {
       const std::size_t size = strlen(base_name) + strlen(extension) + 4;
-      error_name = new char(size);
+      error_name = new char[size];
       snprintf(error_name, size, "%s (%s)", base_name, extension);
       name_allocated = true;
     } else {
@@ -259,7 +259,7 @@ static int x11_error_handler(Display *d, XErrorEvent *err) {
         xcb_errors_ctx, err->request_code, err->minor_code);
     if (minor != nullptr) {
       const std::size_t size = strlen(base_name) + strlen(extension) + 4;
-      code_description = new char(size);
+      code_description = new char[size];
       snprintf(code_description, size, "%s - %s", major, minor);
       code_allocated = true;
     } else {
@@ -284,7 +284,7 @@ static int x11_error_handler(Display *d, XErrorEvent *err) {
   }
   if (code_description == nullptr) {
     const std::size_t size = 37;
-    code_description = new char(size);
+    code_description = new char[size];
     snprintf(code_description, size, "error code: [major: %i, minor: %i]",
              err->request_code, err->minor_code);
     code_allocated = true;
@@ -297,8 +297,8 @@ static int x11_error_handler(Display *d, XErrorEvent *err) {
       error_name, reinterpret_cast<uint64_t>(err->display),
       static_cast<int64_t>(err->resourceid), err->serial, code_description);
 
-  if (name_allocated) free(error_name);
-  if (code_allocated) free(code_description);
+  if (name_allocated) delete[] error_name;
+  if (code_allocated) delete[] code_description;
 
   return 0;
 }