diff --git a/NEWS b/NEWS
index 43eeb6de46b..d04416d3471 100644
--- a/NEWS
+++ b/NEWS
@@ -2,6 +2,10 @@ PHP                                                                        NEWS
 |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 ?? ??? ????, PHP 7.4.0beta2
 
+- Core:
+  . Fixed bug #78340 (Include of stream wrapper not reading whole file).
+    (Nikita)
+
 - Iconv:
   . Fixed bug #78342 (Bus error in configure test for iconv //IGNORE). (Rainer
     Jung)
diff --git a/Zend/tests/bug78340.phpt b/Zend/tests/bug78340.phpt
new file mode 100644
index 00000000000..06acf9ef887
--- /dev/null
+++ b/Zend/tests/bug78340.phpt
@@ -0,0 +1,54 @@
+--TEST--
+Bug #78340: Include of stream wrapper not reading whole file
+--FILE--
+<?php
+
+class lib {
+  public static $files= [];
+
+  private $bytes, $pos;
+
+  function stream_open($path, $mode, $options, $opened_path) {
+    $this->bytes= self::$files[$path];
+    $this->pos= 0;
+    $this->ino= crc32($path);
+    return true;
+  }
+
+  function stream_read($count) {
+    $chunk= substr($this->bytes, $this->pos, $count);
+    $this->pos+= strlen($chunk);
+    return $chunk;
+  }
+
+  function stream_eof() {
+    return $this->pos >= strlen($this->bytes);
+  }
+
+  function stream_close() {
+    $this->bytes= null;
+  }
+
+  function stream_stat() {
+    return [
+      'dev'   => 3632233996,
+      'size'  => strlen($this->bytes),
+      'ino'   => $this->ino
+    ];
+  }
+
+  function stream_set_option($option, $arg1, $arg2) {
+    return false;
+  }
+}
+
+$fill = str_repeat('.', 8192);
+lib::$files['lib://test.php']= '<?php /* '.$fill.' */ function test() { echo "Works!\n"; }';
+stream_wrapper_register('lib', lib::class);
+
+include('lib://test.php');
+test();
+
+?>
+--EXPECT--
+Works!
diff --git a/Zend/zend_stream.c b/Zend/zend_stream.c
index 4dffc310408..3890248a260 100644
--- a/Zend/zend_stream.c
+++ b/Zend/zend_stream.c
@@ -115,7 +115,7 @@ static ssize_t zend_stream_read(zend_file_handle *file_handle, char *buf, size_t
 
 ZEND_API int zend_stream_fixup(zend_file_handle *file_handle, char **buf, size_t *len) /* {{{ */
 {
-	size_t size;
+	size_t file_size;
 
 	if (file_handle->buf) {
 		*buf = file_handle->buf;
@@ -142,26 +142,28 @@ ZEND_API int zend_stream_fixup(zend_file_handle *file_handle, char **buf, size_t
 		file_handle->handle.stream.fsizer = (zend_stream_fsizer_t)zend_stream_stdio_fsizer;
 	}
 
-	size = zend_stream_fsize(file_handle);
-	if (size == (size_t)-1) {
+	file_size = zend_stream_fsize(file_handle);
+	if (file_size == (size_t)-1) {
 		return FAILURE;
 	}
 
-	if (size) {
+	if (file_size) {
 		ssize_t read;
-		*buf = safe_emalloc(1, size, ZEND_MMAP_AHEAD);
-		read = zend_stream_read(file_handle, *buf, size);
+		size_t size = 0;
+		*buf = safe_emalloc(1, file_size, ZEND_MMAP_AHEAD);
+		while ((read = zend_stream_read(file_handle, *buf + size, file_size - size)) > 0) {
+			size += read;
+		}
 		if (read < 0) {
 			efree(*buf);
 			return FAILURE;
 		}
 		file_handle->buf = *buf;
-		file_handle->len = read;
+		file_handle->len = size;
 	} else {
-		size_t remain = 4*1024;
+		size_t size = 0, remain = 4*1024;
 		ssize_t read;
 		*buf = emalloc(remain);
-		size = 0;
 
 		while ((read = zend_stream_read(file_handle, *buf + size, remain)) > 0) {
 			size   += read;