diff --git a/Zend/zend_API.c b/Zend/zend_API.c
index c06d6119b7af..6c42d274c0db 100644
--- a/Zend/zend_API.c
+++ b/Zend/zend_API.c
@@ -19,15 +19,13 @@
    +----------------------------------------------------------------------+
 */
 
-#include "zend.h"
-#include "zend_execute.h"
 #include "zend_API.h"
-#include "zend_modules.h"
+#include "zend_arena.h"
+#include "zend_objects.h" // for zend_objects_new()
 #include "zend_extensions.h"
 #include "zend_constants.h"
-#include "zend_interfaces.h"
+#include "zend_interfaces.h" // for zend_ce_stringable
 #include "zend_exceptions.h"
-#include "zend_closures.h"
 #include "zend_inheritance.h"
 #include "zend_ini.h"
 #include "zend_enum.h"
diff --git a/Zend/zend_API.h b/Zend/zend_API.h
index cbc455eaab0b..44ea4eaf8783 100644
--- a/Zend/zend_API.h
+++ b/Zend/zend_API.h
@@ -22,13 +22,13 @@
 #ifndef ZEND_API_H
 #define ZEND_API_H
 
-#include "zend_modules.h"
-#include "zend_list.h"
-#include "zend_operators.h"
-#include "zend_variables.h"
-#include "zend_execute.h"
-#include "zend_type_info.h"
+#include "zend_compile.h" // for zif_handler
+#include "zend_execute.h" // for get_active_function_or_method_name()
+#include "zend_globals.h" // for struct _zend_compiler_globals used by ZEND_MAP_PTR_GET_IMM()
+#include "zend_globals_macros.h" // for CG() used by ZEND_MAP_PTR_GET_IMM()
+#include "zend_portability.h" // for BEGIN_EXTERN_C
 
+typedef struct _zend_module_entry zend_module_entry;
 
 BEGIN_EXTERN_C()
 
diff --git a/Zend/zend_ast.c b/Zend/zend_ast.c
index 70646856d3a1..0581714ab1ed 100644
--- a/Zend/zend_ast.c
+++ b/Zend/zend_ast.c
@@ -18,13 +18,13 @@
 */
 
 #include "zend_ast.h"
-#include "zend_API.h"
-#include "zend_operators.h"
-#include "zend_language_parser.h"
-#include "zend_smart_str.h"
-#include "zend_exceptions.h"
+#include "zend_API.h" // for array_set_zval_key
+#include "zend_arena.h"
 #include "zend_constants.h"
 #include "zend_enum.h"
+#include "zend_language_parser.h" // for T_*
+#include "zend_smart_str.h"
+#include "zend_exceptions.h" // for zend_throw_error
 
 ZEND_API zend_ast_process_t zend_ast_process = NULL;
 
diff --git a/Zend/zend_ast.h b/Zend/zend_ast.h
index b5df2a55a209..7fc6bef28963 100644
--- a/Zend/zend_ast.h
+++ b/Zend/zend_ast.h
@@ -21,7 +21,9 @@
 #ifndef ZEND_AST_H
 #define ZEND_AST_H
 
-#include "zend.h"
+#include "zend_types.h" // for zval
+
+#include <stdint.h>
 
 #ifndef ZEND_AST_SPEC
 # define ZEND_AST_SPEC 1
diff --git a/Zend/zend_call_stack.c b/Zend/zend_call_stack.c
index dadaa60dcb20..738dfbec5172 100644
--- a/Zend/zend_call_stack.c
+++ b/Zend/zend_call_stack.c
@@ -18,11 +18,11 @@
 
 /* Inspired from Chromium's stack_util.cc */
 
-#include "zend.h"
-#include "zend_globals.h"
-#include "zend_portability.h"
 #include "zend_call_stack.h"
+#include "zend_globals.h"
+
 #include <stdint.h>
+
 #ifdef ZEND_WIN32
 # include <processthreadsapi.h>
 # include <memoryapi.h>
diff --git a/Zend/zend_call_stack.h b/Zend/zend_call_stack.h
index d73c333eeeae..028788ca3c0b 100644
--- a/Zend/zend_call_stack.h
+++ b/Zend/zend_call_stack.h
@@ -19,12 +19,14 @@
 #ifndef ZEND_CALL_STACK_H
 #define ZEND_CALL_STACK_H
 
-#include "zend.h"
-#include "zend_portability.h"
+#include "zend_portability.h" // for zend_always_inline
+
 #ifdef __APPLE__
 # include <pthread.h>
 #endif
 
+#include <stdbool.h>
+
 #ifdef ZEND_CHECK_STACK_LIMIT
 
 typedef struct _zend_call_stack {
diff --git a/Zend/zend_closures.c b/Zend/zend_closures.c
index 4c326a6c79b1..03601ce3fc78 100644
--- a/Zend/zend_closures.c
+++ b/Zend/zend_closures.c
@@ -18,14 +18,11 @@
    +----------------------------------------------------------------------+
 */
 
-#include "zend.h"
-#include "zend_API.h"
 #include "zend_closures.h"
-#include "zend_exceptions.h"
-#include "zend_interfaces.h"
-#include "zend_objects.h"
-#include "zend_objects_API.h"
-#include "zend_globals.h"
+#include "zend_API.h" //for ZEND_METHOD()
+#include "zend_arena.h"
+#include "zend_compile.h" // for union _zend_function
+#include "zend_objects.h" // for zend_object_std_init()
 #include "zend_closures_arginfo.h"
 
 typedef struct _zend_closure {
diff --git a/Zend/zend_closures.h b/Zend/zend_closures.h
index 2d093fa61680..40cb0a36ca3f 100644
--- a/Zend/zend_closures.h
+++ b/Zend/zend_closures.h
@@ -20,6 +20,15 @@
 #ifndef ZEND_CLOSURES_H
 #define ZEND_CLOSURES_H
 
+#include "zend_portability.h" // for BEGIN_EXTERN_C
+
+typedef struct _zend_class_entry zend_class_entry;
+typedef struct _zend_execute_data zend_execute_data;
+typedef union  _zend_function zend_function;
+typedef struct _zend_object zend_object;
+typedef struct _zend_string zend_string;
+typedef struct _zval_struct zval;
+
 BEGIN_EXTERN_C()
 
 /* This macro depends on zend_closure structure layout */
diff --git a/Zend/zend_compile.c b/Zend/zend_compile.c
index 4cb9b9c85305..166d94dc0dd6 100644
--- a/Zend/zend_compile.c
+++ b/Zend/zend_compile.c
@@ -18,23 +18,23 @@
    +----------------------------------------------------------------------+
 */
 
-#include <zend_language_parser.h>
-#include "zend.h"
-#include "zend_attributes.h"
 #include "zend_compile.h"
+#include "zend_API.h" // for zend_get_object_type()
+#include "zend_arena.h"
+#include "zend_attributes.h"
 #include "zend_constants.h"
-#include "zend_llist.h"
-#include "zend_API.h"
-#include "zend_exceptions.h"
-#include "zend_interfaces.h"
-#include "zend_virtual_cwd.h"
-#include "zend_multibyte.h"
-#include "zend_language_scanner.h"
-#include "zend_inheritance.h"
-#include "zend_vm.h"
 #include "zend_enum.h"
-#include "zend_observer.h"
-#include "zend_call_stack.h"
+#include "zend_exceptions.h" // for zend_throw_exception_ex()
+#include "zend_globals.h" // struct _zend_compiler_globals
+#include "zend_globals_macros.h" // for CG()
+#include "zend_inheritance.h" // for zend_do_link_class()
+#include "zend_language_parser.h"
+#include "zend_language_scanner.h"
+#include "zend_list.h" // for zend_init_rsrc_list()
+#include "zend_observer.h" // for zend_observer_function_declared_notify()
+#include "zend_type_info.h" // for MAY_BE_*
+#include "zend_virtual_cwd.h" // for IS_SLASH_P, DEFAULT_SLASH
+#include "zend_vm.h" // for ZEND_VM_SET_OPCODE_HANDLER()
 
 #define SET_NODE(target, src) do { \
 		target ## _type = (src)->op_type; \
diff --git a/Zend/zend_compile.h b/Zend/zend_compile.h
index fa9e582869fb..6f7a7d42101c 100644
--- a/Zend/zend_compile.h
+++ b/Zend/zend_compile.h
@@ -20,12 +20,12 @@
 #ifndef ZEND_COMPILE_H
 #define ZEND_COMPILE_H
 
-#include "zend.h"
+#include "zend.h" // for INTERNAL_FUNCTION_PARAMETERS
 #include "zend_ast.h"
+#include "zend_portability.h" //for ZEND_FASTCALL
+#include "zend_types.h" // for zend_uchar
 
-#include <stdarg.h>
-
-#include "zend_llist.h"
+#include <stdint.h>
 
 #define SET_UNUSED(op) do { \
 	op ## _type = IS_UNUSED; \
@@ -758,8 +758,6 @@ struct _zend_execute_data {
 
 #define ZEND_EXTRA_VALUE 1
 
-#include "zend_globals.h"
-
 typedef enum _zend_compile_position {
 	ZEND_COMPILE_POSITION_AT_SHEBANG = 0,
 	ZEND_COMPILE_POSITION_AT_OPEN_TAG,
diff --git a/Zend/zend_enum.c b/Zend/zend_enum.c
index 3e455b702cbf..11c62d83e1a7 100644
--- a/Zend/zend_enum.c
+++ b/Zend/zend_enum.c
@@ -16,13 +16,13 @@
    +----------------------------------------------------------------------+
 */
 
-#include "zend.h"
-#include "zend_API.h"
-#include "zend_compile.h"
+#include "zend_enum.h"
+#include "zend_arena.h" // ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO_EX2
+#include "zend_API.h" // for INIT_CLASS_ENTRY_EX()
 #include "zend_enum_arginfo.h"
 #include "zend_interfaces.h"
-#include "zend_enum.h"
-#include "zend_extensions.h"
+#include "zend_extensions.h" // for zend_internal_run_time_cache_reserved_size()
+#include "zend_objects.h" // for zend_objects_new()
 #include "zend_observer.h"
 
 #define ZEND_ENUM_DISALLOW_MAGIC_METHOD(propertyName, methodName) \
diff --git a/Zend/zend_enum.h b/Zend/zend_enum.h
index dbb230c4175c..895100f09229 100644
--- a/Zend/zend_enum.h
+++ b/Zend/zend_enum.h
@@ -19,8 +19,11 @@
 #ifndef ZEND_ENUM_H
 #define ZEND_ENUM_H
 
-#include "zend.h"
-#include "zend_types.h"
+#include "zend_compile.h" // for OBJ_PROP_NUM
+#include "zend_portability.h" // for BEGIN_EXTERN_C
+
+typedef struct _zend_class_entry zend_class_entry;
+typedef struct _zend_function_entry zend_function_entry;
 
 BEGIN_EXTERN_C()
 
diff --git a/Zend/zend_execute.h b/Zend/zend_execute.h
index b7aa52764718..300db3902f4a 100644
--- a/Zend/zend_execute.h
+++ b/Zend/zend_execute.h
@@ -22,15 +22,12 @@
 #define ZEND_EXECUTE_H
 
 #include "zend_compile.h" // for zend_op_array
+#include "zend_globals.h" // for struct _zend_executor_globals
+#include "zend_globals_macros.h" // for EG()
 #include "zend_list.h" // for zend_rsrc_list_get_rsrc_type()
 #include "zend_portability.h" // for BEGIN_EXTERN_C
 #include "zend_types.h" // for zend_execute_data
 
-#if ZEND_DEBUG
-#include "zend_globals.h" // for struct _zend_executor_globals
-#include "zend_globals_macros.h" // for EG()
-#endif
-
 BEGIN_EXTERN_C()
 struct _zend_fcall_info;
 ZEND_API extern void (*zend_execute_ex)(zend_execute_data *execute_data);
diff --git a/Zend/zend_gc.c b/Zend/zend_gc.c
index 66324672b1e9..ccd75a0706b3 100644
--- a/Zend/zend_gc.c
+++ b/Zend/zend_gc.c
@@ -66,9 +66,14 @@
  *
  * @see http://researcher.watson.ibm.com/researcher/files/us-bacon/Bacon01Concurrent.pdf
  */
-#include "zend.h"
-#include "zend_API.h"
-#include "zend_fibers.h"
+
+#include "zend_gc.h"
+#include "zend_alloc.h" // for ZEND_MM_OVERHEAD
+#include "zend_fibers.h" // for zend_fiber_switch_block()
+#include "zend_globals.h" // for struct _zend_executor_globals
+#include "zend_globals_macros.h" // for EG()
+#include "zend_objects.h" // for zend_objects_destroy_object()
+#include "zend.h" // for zend_error()
 
 #ifndef GC_BENCH
 # define GC_BENCH 0
diff --git a/Zend/zend_gc.h b/Zend/zend_gc.h
index 0589e193f4a1..0ee7e38460e7 100644
--- a/Zend/zend_gc.h
+++ b/Zend/zend_gc.h
@@ -20,6 +20,9 @@
 #ifndef ZEND_GC_H
 #define ZEND_GC_H
 
+#include "zend_portability.h" // for BEGIN_EXTERN_C
+#include "zend_types.h" // for GC_TYPE_INFO()
+
 BEGIN_EXTERN_C()
 
 typedef struct _zend_gc_status {
diff --git a/Zend/zend_globals_macros.h b/Zend/zend_globals_macros.h
index 59b3daca53fd..60e8def86d5a 100644
--- a/Zend/zend_globals_macros.h
+++ b/Zend/zend_globals_macros.h
@@ -20,6 +20,8 @@
 #ifndef ZEND_GLOBALS_MACROS_H
 #define ZEND_GLOBALS_MACROS_H
 
+#include "zend_portability.h" // for BEGIN_EXTERN_C
+
 typedef struct _zend_compiler_globals zend_compiler_globals;
 typedef struct _zend_executor_globals zend_executor_globals;
 typedef struct _zend_php_scanner_globals zend_php_scanner_globals;
diff --git a/Zend/zend_inheritance.c b/Zend/zend_inheritance.c
index b45c16ef9152..29141125a59a 100644
--- a/Zend/zend_inheritance.c
+++ b/Zend/zend_inheritance.c
@@ -18,6 +18,7 @@
 */
 
 #include "zend.h"
+#include "zend_arena.h"
 #include "zend_API.h"
 #include "zend_compile.h"
 #include "zend_execute.h"
diff --git a/Zend/zend_interfaces.c b/Zend/zend_interfaces.c
index d05310b737b0..52cc476578bd 100644
--- a/Zend/zend_interfaces.c
+++ b/Zend/zend_interfaces.c
@@ -16,11 +16,13 @@
    +----------------------------------------------------------------------+
 */
 
+#include "zend_interfaces.h"
 #include "zend.h"
 #include "zend_API.h"
-#include "zend_interfaces.h"
+#include "zend_arena.h"
 #include "zend_exceptions.h"
 #include "zend_interfaces_arginfo.h"
+#include "zend_objects.h" // for zend_object_std_init()
 
 ZEND_API zend_class_entry *zend_ce_traversable;
 ZEND_API zend_class_entry *zend_ce_aggregate;
diff --git a/Zend/zend_interfaces.h b/Zend/zend_interfaces.h
index 883e482f510c..e8291213d7fb 100644
--- a/Zend/zend_interfaces.h
+++ b/Zend/zend_interfaces.h
@@ -19,8 +19,12 @@
 #ifndef ZEND_INTERFACES_H
 #define ZEND_INTERFACES_H
 
-#include "zend.h"
-#include "zend_API.h"
+#include "zend_iterators.h" // for zend_object_iterator
+#include "zend_portability.h" // for BEGIN_EXTERN_C
+
+typedef struct _zend_class_entry zend_class_entry;
+typedef struct _zend_serialize_data zend_serialize_data;
+typedef struct _zend_unserialize_data zend_unserialize_data;
 
 BEGIN_EXTERN_C()
 
diff --git a/Zend/zend_iterators.c b/Zend/zend_iterators.c
index f67033b11161..fd5a0895b2a0 100644
--- a/Zend/zend_iterators.c
+++ b/Zend/zend_iterators.c
@@ -17,8 +17,10 @@
    +----------------------------------------------------------------------+
 */
 
-#include "zend.h"
-#include "zend_API.h"
+#include "zend_iterators.h"
+#include "zend_objects.h"
+#include "zend_object_handlers.h"
+#include "zend_API.h" // for INIT_CLASS_ENTRY
 
 static zend_class_entry zend_iterator_class_entry;
 
diff --git a/Zend/zend_iterators.h b/Zend/zend_iterators.h
index 5e7451f7eacc..98337961948f 100644
--- a/Zend/zend_iterators.h
+++ b/Zend/zend_iterators.h
@@ -17,6 +17,11 @@
    +----------------------------------------------------------------------+
 */
 
+#ifndef ZEND_ITERATORS_H
+#define ZEND_ITERATORS_H
+
+#include "zend_types.h" // for zval
+
 /* These iterators were designed to operate within the foreach()
  * structures provided by the engine, but could be extended for use
  * with other iterative engine opcodes.
@@ -89,3 +94,5 @@ ZEND_API void zend_iterator_dtor(zend_object_iterator *iter);
 
 ZEND_API void zend_register_iterator_wrapper(void);
 END_EXTERN_C()
+
+#endif /* ZEND_ITERATORS_H */
diff --git a/Zend/zend_language_scanner.h b/Zend/zend_language_scanner.h
index ca32329a557f..c93b0fea56ed 100644
--- a/Zend/zend_language_scanner.h
+++ b/Zend/zend_language_scanner.h
@@ -20,6 +20,14 @@
 #ifndef ZEND_SCANNER_H
 #define ZEND_SCANNER_H
 
+#include "zend_globals.h" // for zend_php_scanner_event
+#include "zend_multibyte.h" // for zend_encoding_filter
+#include "zend_portability.h" // for BEGIN_EXTERN_C
+#include "zend_ptr_stack.h"
+#include "zend_stack.h"
+
+typedef struct _zend_file_handle zend_file_handle;
+
 typedef struct _zend_lex_state {
 	unsigned int yy_leng;
 	unsigned char *yy_start;
diff --git a/Zend/zend_language_scanner.l b/Zend/zend_language_scanner.l
index c73a50948d6b..c1ba518ddfba 100644
--- a/Zend/zend_language_scanner.l
+++ b/Zend/zend_language_scanner.l
@@ -27,6 +27,7 @@
 # define YYDEBUG(s, c)
 #endif
 
+#include "zend_language_scanner.h"
 #include "zend_language_scanner_defs.h"
 
 #include <errno.h>
@@ -35,9 +36,9 @@
 # include <Winuser.h>
 #endif
 #include "zend_alloc.h"
+#include "zend_arena.h"
 #include <zend_language_parser.h>
 #include "zend_compile.h"
-#include "zend_language_scanner.h"
 #include "zend_highlight.h"
 #include "zend_constants.h"
 #include "zend_variables.h"
diff --git a/Zend/zend_list.c b/Zend/zend_list.c
index 51ef3e1d92eb..6b2742c6808d 100644
--- a/Zend/zend_list.c
+++ b/Zend/zend_list.c
@@ -19,10 +19,12 @@
 
 /* resource lists */
 
-#include "zend.h"
 #include "zend_list.h"
-#include "zend_API.h"
-#include "zend_globals.h"
+#include "zend_execute.h" // for get_active_class_name()
+#include "zend_globals.h" // for struct _zend_executor_globals
+#include "zend_globals_macros.h" // for EG()
+#include "zend_hash.h"
+#include "zend_types.h" // for zval
 
 ZEND_API int le_index_ptr;
 
diff --git a/Zend/zend_list.h b/Zend/zend_list.h
index 680915121e2a..643abe65023c 100644
--- a/Zend/zend_list.h
+++ b/Zend/zend_list.h
@@ -20,8 +20,12 @@
 #ifndef ZEND_LIST_H
 #define ZEND_LIST_H
 
-#include "zend_hash.h"
-#include "zend_globals.h"
+#include "zend_portability.h" // for BEGIN_EXTERN_C
+
+typedef struct _zend_array HashTable;
+typedef struct _zend_resource zend_resource;
+typedef struct _zend_string zend_string;
+typedef struct _zval_struct zval;
 
 BEGIN_EXTERN_C()
 
diff --git a/Zend/zend_llist.c b/Zend/zend_llist.c
index 8c42b2494ea0..cdc018ae6278 100644
--- a/Zend/zend_llist.c
+++ b/Zend/zend_llist.c
@@ -17,8 +17,8 @@
    +----------------------------------------------------------------------+
 */
 
-#include "zend.h"
 #include "zend_llist.h"
+#include "zend_alloc.h" //for pemalloc()
 #include "zend_sort.h"
 
 ZEND_API void zend_llist_init(zend_llist *l, size_t size, llist_dtor_func_t dtor, unsigned char persistent)
diff --git a/Zend/zend_llist.h b/Zend/zend_llist.h
index cce5ad5ce95a..e68be3cb2011 100644
--- a/Zend/zend_llist.h
+++ b/Zend/zend_llist.h
@@ -20,6 +20,8 @@
 #ifndef ZEND_LLIST_H
 #define ZEND_LLIST_H
 
+#include "zend_portability.h" // for BEGIN_EXTERN_C
+
 typedef struct _zend_llist_element {
 	struct _zend_llist_element *next;
 	struct _zend_llist_element *prev;
diff --git a/Zend/zend_objects.c b/Zend/zend_objects.c
index df76fa0bb8dc..f82f577df512 100644
--- a/Zend/zend_objects.c
+++ b/Zend/zend_objects.c
@@ -18,13 +18,14 @@
    +----------------------------------------------------------------------+
 */
 
-#include "zend.h"
-#include "zend_globals.h"
-#include "zend_variables.h"
-#include "zend_API.h"
-#include "zend_interfaces.h"
-#include "zend_exceptions.h"
-#include "zend_weakrefs.h"
+#include "zend_objects.h"
+#include "zend_objects_API.h"
+#include "zend_exceptions.h" // for zend_rethrow_exception()
+#include "zend_execute.h" // for ZEND_REF_HAS_TYPE_SOURCES
+#include "zend_types.h" // for GC_SET_REFCOUNT()
+#include "zend_weakrefs.h" // for zend_weakrefs_notify()
+#include "zend.h" // for struct _zend_class_entry
+#include "zend_API.h" // for zend_call_known_instance_method_with_0_params()
 
 static zend_always_inline void _zend_object_std_init(zend_object *object, zend_class_entry *ce)
 {
diff --git a/Zend/zend_objects.h b/Zend/zend_objects.h
index 91d388154dd1..c998e9c60a29 100644
--- a/Zend/zend_objects.h
+++ b/Zend/zend_objects.h
@@ -20,7 +20,10 @@
 #ifndef ZEND_OBJECTS_H
 #define ZEND_OBJECTS_H
 
-#include "zend.h"
+#include "zend_portability.h" // for BEGIN_EXTERN_C
+
+typedef struct _zend_class_entry zend_class_entry;
+typedef struct _zend_object zend_object;
 
 BEGIN_EXTERN_C()
 ZEND_API void ZEND_FASTCALL zend_object_std_init(zend_object *object, zend_class_entry *ce);
diff --git a/Zend/zend_objects_API.c b/Zend/zend_objects_API.c
index 80f5b747db71..140219c07779 100644
--- a/Zend/zend_objects_API.c
+++ b/Zend/zend_objects_API.c
@@ -18,11 +18,12 @@
    +----------------------------------------------------------------------+
 */
 
+#include "zend_objects_API.h"
+#include "zend_objects.h" // for zend_objects_destroy_object()
 #include "zend.h"
 #include "zend_globals.h"
 #include "zend_variables.h"
 #include "zend_API.h"
-#include "zend_objects_API.h"
 #include "zend_fibers.h"
 
 ZEND_API void ZEND_FASTCALL zend_objects_store_init(zend_objects_store *objects, uint32_t init_size)
diff --git a/Zend/zend_objects_API.h b/Zend/zend_objects_API.h
index 7a9a3a00082c..c643a250ce75 100644
--- a/Zend/zend_objects_API.h
+++ b/Zend/zend_objects_API.h
@@ -20,8 +20,12 @@
 #ifndef ZEND_OBJECTS_API_H
 #define ZEND_OBJECTS_API_H
 
-#include "zend.h"
-#include "zend_compile.h"
+#include "zend_portability.h" // for BEGIN_EXTERN_C
+#include "zend_gc.h" // for GC_MAY_LEAK
+#include "zend_compile.h" // for ZEND_ACC_USE_GUARDS
+#include "zend.h" // for _zend_class_entry
+
+typedef struct _zend_object zend_object;
 
 #define OBJ_BUCKET_INVALID			(1<<0)
 
diff --git a/Zend/zend_observer.c b/Zend/zend_observer.c
index 79929bfdd80e..7ff183f0efac 100644
--- a/Zend/zend_observer.c
+++ b/Zend/zend_observer.c
@@ -18,10 +18,10 @@
 */
 
 #include "zend_observer.h"
-
-#include "zend_extensions.h"
+#include "zend_fibers.h"
+#include "zend_extensions.h" // for zend_get_op_array_extension_handles()
 #include "zend_llist.h"
-#include "zend_vm.h"
+#include "zend_vm.h" // for ZEND_VM_SET_OPCODE_HANDLER()
 
 #define ZEND_OBSERVER_DATA(function) \
 	ZEND_OP_ARRAY_EXTENSION((&(function)->common), zend_observer_fcall_op_array_extension)
diff --git a/Zend/zend_observer.h b/Zend/zend_observer.h
index fc4d9a62c890..8c5b20b3495d 100644
--- a/Zend/zend_observer.h
+++ b/Zend/zend_observer.h
@@ -20,9 +20,15 @@
 #ifndef ZEND_OBSERVER_H
 #define ZEND_OBSERVER_H
 
-#include "zend.h"
-#include "zend_compile.h"
-#include "zend_fibers.h"
+#include "zend_portability.h" // for BEGIN_EXTERN_C
+
+typedef struct _zend_class_entry zend_class_entry;
+typedef struct _zend_execute_data zend_execute_data;
+typedef struct _zend_fiber_context zend_fiber_context;
+typedef union  _zend_function zend_function;
+typedef struct _zend_op_array zend_op_array;
+typedef struct _zend_string zend_string;
+typedef struct _zval_struct zval;
 
 BEGIN_EXTERN_C()
 
diff --git a/Zend/zend_weakrefs.c b/Zend/zend_weakrefs.c
index db95b13a7254..19cbe6fa37ef 100644
--- a/Zend/zend_weakrefs.c
+++ b/Zend/zend_weakrefs.c
@@ -14,11 +14,11 @@
    +----------------------------------------------------------------------+
 */
 
-#include "zend.h"
-#include "zend_interfaces.h"
-#include "zend_objects_API.h"
 #include "zend_weakrefs.h"
+#include "zend_API.h" // for ZEND_BEGIN_ARG_INFO_EX
+#include "zend_objects.h" // for zend_object_std_init()
 #include "zend_weakrefs_arginfo.h"
+#include "zend_interfaces.h" // for zend_create_internal_iterator_zval()
 
 typedef struct _zend_weakref {
 	zend_object *referent;
diff --git a/Zend/zend_weakrefs.h b/Zend/zend_weakrefs.h
index 506e2e9d40c5..6e3f108646c3 100644
--- a/Zend/zend_weakrefs.h
+++ b/Zend/zend_weakrefs.h
@@ -17,7 +17,8 @@
 #ifndef ZEND_WEAKREFS_H
 #define ZEND_WEAKREFS_H
 
-#include "zend_alloc.h"
+#include "zend_portability.h" // for BEGIN_EXTERN_C
+#include "zend_types.h" // for zval
 
 BEGIN_EXTERN_C()
 
diff --git a/ext/opcache/ZendAccelerator.h b/ext/opcache/ZendAccelerator.h
index 6ecc2c2bc9df..5cda73bb1d6f 100644
--- a/ext/opcache/ZendAccelerator.h
+++ b/ext/opcache/ZendAccelerator.h
@@ -50,6 +50,7 @@
 
 #include "zend_extensions.h"
 #include "zend_compile.h"
+#include "zend_modules.h" // for INIT_FUNC_ARGS
 
 #include "Optimizer/zend_optimizer.h"
 #include "zend_accelerator_hash.h"
diff --git a/main/php.h b/main/php.h
index b7101ed22f0a..cb1ab5ea7c8e 100644
--- a/main/php.h
+++ b/main/php.h
@@ -29,6 +29,8 @@
 
 #include "php_version.h"
 #include "zend.h"
+#include "zend_arena.h"
+#include "zend_objects.h"
 #include "zend_sort.h"
 #include "php_compat.h"