diff --git a/compiler/pipes/optimization.cpp b/compiler/pipes/optimization.cpp
index 33a28eaaad..1ce099e507 100644
--- a/compiler/pipes/optimization.cpp
+++ b/compiler/pipes/optimization.cpp
@@ -448,6 +448,11 @@ void OptimizationPass::on_finish() {
     class_id->members.for_each([this](ClassMemberStaticField &static_field) {
       if (static_field.var->init_val) {
         run_function_pass(static_field.var->init_val, this);
+        // a static field's init value is stored in php globals and is reset via hard_reset_var()
+        // on every request startup, where memory allocations are forbidden;
+        // its constant initializer must therefore have exactly the same C++ type as the field itself
+        // (otherwise a converting copy_from() is generated, which allocates memory and crashes)
+        explicit_cast_array_type(static_field.var->init_val, tinf::get_type(static_field.var));
       }
     });
   }
diff --git a/tests/phpt/cl/200_static_field_array_infer.php b/tests/phpt/cl/200_static_field_array_infer.php
new file mode 100644
index 0000000000..a97a89e7de
--- /dev/null
+++ b/tests/phpt/cl/200_static_field_array_infer.php
@@ -0,0 +1,29 @@
+@ok
+<?php
+
+/*
+ * This test checks that the type of $filtered_ids_by_reason's init value
+ * is inferred as array<int>. Previously, it could be inferred as
+ * array<Unknown>.
+ *
+ * With array<Unknown>, a conversion to array<int> would be required, which
+ * is not allowed in static variable initialization: the init value must
+ * have exactly the same C++ type as the field itself.
+ */
+
+class SearchFilter {
+  public const REASON_A = 'reason_a';
+  public const REASON_B = 'reason_b';
+  public const REASON_C = 'reason_c';
+  public const REASON_D = 'reason_d';
+
+  /** @var int[][] */
+  private static $filtered_ids_by_reason = [
+    self::REASON_A => [],
+    self::REASON_B => [],
+    self::REASON_C => [],
+    self::REASON_D => [],
+  ];
+}
+
+var_dump(new SearchFilter === new SearchFilter);