diff --git a/build/php.m4 b/build/php.m4
index 7392876478cd8..51fa37446a509 100644
--- a/build/php.m4
+++ b/build/php.m4
@@ -2416,6 +2416,7 @@ AC_DEFUN([PHP_CHECK_STDINT_TYPES], [
   AC_CHECK_SIZEOF([long])
   AC_CHECK_SIZEOF([long long])
   AC_CHECK_SIZEOF([size_t])
+  AC_CHECK_SIZEOF([off_t])
   AC_CHECK_TYPES([int8, int16, int32, int64, int8_t, int16_t, int32_t, int64_t, uint8, uint16, uint32, uint64, uint8_t, uint16_t, uint32_t, uint64_t, u_int8_t, u_int16_t, u_int32_t, u_int64_t], [], [], [
 #if HAVE_STDINT_H
 # include <stdint.h>
diff --git a/ext/ffi/tests/bug79532.phpt b/ext/ffi/tests/bug79532.phpt
new file mode 100644
index 0000000000000..b6887dc7cb282
--- /dev/null
+++ b/ext/ffi/tests/bug79532.phpt
@@ -0,0 +1,38 @@
+--TEST--
+Bug #79532 (sizeof off_t can be wrong)
+--SKIPIF--
+<?php
+if (!extension_loaded('ffi')) die('skip ffi extension not available');
+if (!extension_loaded('zend-test')) die('skip zend-test extension not available');
+?>
+--FILE--
+<?php
+require_once('utils.inc');
+
+$header = <<<HEADER
+void bug79532(off_t *array, size_t elems);
+HEADER;
+
+if (PHP_OS_FAMILY !== 'Windows') {
+    $ffi = FFI::cdef($header);
+} else {
+    try {
+        $ffi = FFI::cdef($header, 'php_zend_test.dll');
+    } catch (FFI\Exception $ex) {
+        $ffi = FFI::cdef($header, ffi_get_php_dll_name());
+    }
+}
+
+$array = FFI::new("off_t[3]");
+$ffi->bug79532($array, 3);
+var_dump($array);
+?>
+--EXPECTF--
+object(FFI\CData:int%d_t[3])#%d (3) {
+  [0]=>
+  int(0)
+  [1]=>
+  int(1)
+  [2]=>
+  int(2)
+}
diff --git a/ext/pdo_pgsql/pdo_pgsql.c b/ext/pdo_pgsql/pdo_pgsql.c
index 8d60fe420b0b0..8d4158198dfbe 100644
--- a/ext/pdo_pgsql/pdo_pgsql.c
+++ b/ext/pdo_pgsql/pdo_pgsql.c
@@ -29,6 +29,7 @@
 #include "php_pdo_pgsql_int.h"
 
 #ifdef HAVE_PG_CONFIG_H
+#undef SIZEOF_OFF_T
 #include <pg_config.h>
 #endif
 
diff --git a/ext/pdo_pgsql/pgsql_driver.c b/ext/pdo_pgsql/pgsql_driver.c
index b6f008071c628..403bfd611ae1e 100644
--- a/ext/pdo_pgsql/pgsql_driver.c
+++ b/ext/pdo_pgsql/pgsql_driver.c
@@ -31,6 +31,7 @@
 #include "pdo/php_pdo_driver.h"
 #include "pdo/php_pdo_error.h"
 #include "ext/standard/file.h"
+#undef SIZEOF_OFF_T
 #include "pg_config.h" /* needed for PG_VERSION */
 #include "php_pdo_pgsql.h"
 #include "php_pdo_pgsql_int.h"
diff --git a/ext/pgsql/php_pgsql.h b/ext/pgsql/php_pgsql.h
index cecd2cc95b33e..a6c884d912b7c 100644
--- a/ext/pgsql/php_pgsql.h
+++ b/ext/pgsql/php_pgsql.h
@@ -51,6 +51,7 @@ extern zend_module_entry pgsql_module_entry;
 #endif
 
 #ifdef HAVE_PG_CONFIG_H
+#undef SIZEOF_OFF_T
 #include <pg_config.h>
 #endif
 
diff --git a/ext/zend_test/php_test.h b/ext/zend_test/php_test.h
index 325484c434805..da57f7efc9a0e 100644
--- a/ext/zend_test/php_test.h
+++ b/ext/zend_test/php_test.h
@@ -38,5 +38,6 @@ struct bug79096 {
 };
 
 ZEND_API struct bug79096 bug79096(void);
+ZEND_API void bug79532(off_t *array, size_t elems);
 
 #endif
diff --git a/ext/zend_test/test.c b/ext/zend_test/test.c
index b097a2412b9f5..dfae54e880d6c 100644
--- a/ext/zend_test/test.c
+++ b/ext/zend_test/test.c
@@ -328,3 +328,11 @@ struct bug79096 bug79096(void)
   b.b = 1;
   return b;
 }
+
+void bug79532(off_t *array, size_t elems)
+{
+	int i;
+	for (i = 0; i < elems; i++) {
+		array[i] = i;
+	}
+}
diff --git a/win32/build/config.w32.h.in b/win32/build/config.w32.h.in
index 864bc882ff612..36a45fb76c186 100644
--- a/win32/build/config.w32.h.in
+++ b/win32/build/config.w32.h.in
@@ -101,6 +101,7 @@
 # define SIZEOF_SIZE_T 4
 # define SIZEOF_PTRDIFF_T 4
 #endif
+#define SIZEOF_OFF_T 4
 #define HAVE_FNMATCH
 #define HAVE_GLOB
 #define PHP_SHLIB_SUFFIX "dll"