diff --git a/ext/opcache/ZendAccelerator.c b/ext/opcache/ZendAccelerator.c
index 92d0ee5dbdd..32cf5130132 100644
--- a/ext/opcache/ZendAccelerator.c
+++ b/ext/opcache/ZendAccelerator.c
@@ -2864,7 +2864,7 @@ static zend_result zend_accel_init_shm(void)
 	zend_shared_alloc_lock();
 
 	if (ZCG(accel_directives).interned_strings_buffer) {
-		accel_shared_globals_size = ZCG(accel_directives).interned_strings_buffer * 1024 * 1024;
+		accel_shared_globals_size = sizeof(zend_accel_shared_globals) + ZCG(accel_directives).interned_strings_buffer * 1024 * 1024;
 	} else {
 		/* Make sure there is always at least one interned string hash slot,
 		 * so the table can be queried unconditionally. */
@@ -2905,7 +2905,7 @@ static zend_result zend_accel_init_shm(void)
 		ZCSG(interned_strings).top =
 			ZCSG(interned_strings).start;
 		ZCSG(interned_strings).end =
-			(zend_string*)((char*)accel_shared_globals +
+			(zend_string*)((char*)(accel_shared_globals + 1) + /* table data is stored after accel_shared_globals */
 				ZCG(accel_directives).interned_strings_buffer * 1024 * 1024);
 		ZCSG(interned_strings).saved_top = NULL;
 
diff --git a/ext/opcache/tests/gh11715.phpt b/ext/opcache/tests/gh11715.phpt
new file mode 100644
index 00000000000..1f843e26879
--- /dev/null
+++ b/ext/opcache/tests/gh11715.phpt
@@ -0,0 +1,19 @@
+--TEST--
+GH-11715 (opcache.interned_strings_buffer either has no effect or opcache_get_status() / phpinfo() is wrong)
+--EXTENSIONS--
+opcache
+--INI--
+opcache.enable=1
+opcache.enable_cli=1
+opcache.interned_strings_buffer=16
+--FILE--
+<?php
+
+$info = opcache_get_status()['interned_strings_usage'];
+var_dump($info['used_memory'] + $info['free_memory']);
+var_dump($info['buffer_size']);
+
+?>
+--EXPECT--
+int(16777216)
+int(16777216)
diff --git a/ext/opcache/zend_accelerator_module.c b/ext/opcache/zend_accelerator_module.c
index 6b1c872fe05..5181af8d8c9 100644
--- a/ext/opcache/zend_accelerator_module.c
+++ b/ext/opcache/zend_accelerator_module.c
@@ -41,7 +41,7 @@
 #define STRING_NOT_NULL(s) (NULL == (s)?"":s)
 #define MIN_ACCEL_FILES 200
 #define MAX_ACCEL_FILES 1000000
-#define MAX_INTERNED_STRINGS_BUFFER_SIZE ((zend_long)((UINT32_MAX-PLATFORM_ALIGNMENT)/(1024*1024)))
+#define MAX_INTERNED_STRINGS_BUFFER_SIZE ((zend_long)((UINT32_MAX-PLATFORM_ALIGNMENT-sizeof(zend_accel_shared_globals))/(1024*1024)))
 #define TOKENTOSTR(X) #X
 
 static zif_handler orig_file_exists = NULL;
@@ -525,7 +525,7 @@ void zend_accel_info(ZEND_MODULE_INFO_FUNC_ARGS)
 			snprintf(buf, sizeof(buf), "%zu", ZSMMG(wasted_shared_memory));
 			php_info_print_table_row(2, "Wasted memory", buf);
 			if (ZCSG(interned_strings).start && ZCSG(interned_strings).end) {
-				snprintf(buf, sizeof(buf), "%zu", (size_t)((char*)ZCSG(interned_strings).top - (char*)ZCSG(interned_strings).start));
+				snprintf(buf, sizeof(buf), "%zu", (size_t)((char*)ZCSG(interned_strings).top - (char*)(accel_shared_globals + 1)));
 				php_info_print_table_row(2, "Interned Strings Used memory", buf);
 				snprintf(buf, sizeof(buf), "%zu", (size_t)((char*)ZCSG(interned_strings).end - (char*)ZCSG(interned_strings).top));
 				php_info_print_table_row(2, "Interned Strings Free memory", buf);
@@ -686,8 +686,8 @@ ZEND_FUNCTION(opcache_get_status)
 		zval interned_strings_usage;
 
 		array_init(&interned_strings_usage);
-		add_assoc_long(&interned_strings_usage, "buffer_size", (char*)ZCSG(interned_strings).end - (char*)ZCSG(interned_strings).start);
-		add_assoc_long(&interned_strings_usage, "used_memory", (char*)ZCSG(interned_strings).top - (char*)ZCSG(interned_strings).start);
+		add_assoc_long(&interned_strings_usage, "buffer_size", (char*)ZCSG(interned_strings).end - (char*)(accel_shared_globals + 1));
+		add_assoc_long(&interned_strings_usage, "used_memory", (char*)ZCSG(interned_strings).top - (char*)(accel_shared_globals + 1));
 		add_assoc_long(&interned_strings_usage, "free_memory", (char*)ZCSG(interned_strings).end - (char*)ZCSG(interned_strings).top);
 		add_assoc_long(&interned_strings_usage, "number_of_strings", ZCSG(interned_strings).nNumOfElements);
 		add_assoc_zval(return_value, "interned_strings_usage", &interned_strings_usage);