diff --git a/NEWS b/NEWS
index 3d8abc9d9a6..dec9a664e8c 100644
--- a/NEWS
+++ b/NEWS
@@ -3,6 +3,8 @@ PHP                                                                        NEWS
 01 Oct 2015, PHP 7.0.0 RC 4
 
 - Core:
+  . Fixed bug #70547 (unsetting function variables corrupts backtrace).
+    (Laruence)
   . Fixed bug #70528 (assert() with instanceof adds apostrophes around class
     name). (Laruence)
   . Fixed bug #70481 (Memory leak in auto_global_copy_ctor() in ZTS build).
diff --git a/Zend/tests/bug70547.phpt b/Zend/tests/bug70547.phpt
new file mode 100644
index 00000000000..195495dcdc0
--- /dev/null
+++ b/Zend/tests/bug70547.phpt
@@ -0,0 +1,48 @@
+--TEST--
+Bug #70547 (unsetting function variables corrupts backtrace)
+--FILE--
+<?php
+function brokenTrace($arg1, $arg2, $arg3){
+    backtraceWrapper();
+	unset($arg3);
+    backtraceWrapper();
+    unset($arg1);
+    backtraceWrapper();
+    unset($arg2);
+    backtraceWrapper();
+}
+brokenTrace("1st", "2nd", "3th", "4th");
+function backtraceWrapper(){
+    $bt = debug_backtrace();
+    var_dump($bt[1]['args']);
+}
+?>
+--EXPECT--
+array(4) {
+  [0]=>
+  string(3) "1st"
+  [1]=>
+  string(3) "2nd"
+  [2]=>
+  string(3) "3th"
+  [3]=>
+  string(3) "4th"
+}
+array(3) {
+  [0]=>
+  string(3) "1st"
+  [1]=>
+  string(3) "2nd"
+  [2]=>
+  string(3) "4th"
+}
+array(2) {
+  [0]=>
+  string(3) "2nd"
+  [1]=>
+  string(3) "4th"
+}
+array(1) {
+  [0]=>
+  string(3) "4th"
+}
diff --git a/Zend/zend_builtin_functions.c b/Zend/zend_builtin_functions.c
index e3f087b356c..b0e4f6ab021 100644
--- a/Zend/zend_builtin_functions.c
+++ b/Zend/zend_builtin_functions.c
@@ -2233,8 +2233,12 @@ static void debug_backtrace_get_args(zend_execute_data *call, zval *arg_array) /
 
 				if (ZEND_CALL_NUM_ARGS(call) > first_extra_arg) {
 					while (i < first_extra_arg) {
-						if (Z_OPT_REFCOUNTED_P(p)) Z_ADDREF_P(p);
-						ZEND_HASH_FILL_ADD(p);
+						if (Z_TYPE_INFO_P(p) != IS_UNDEF) {
+							if (Z_OPT_REFCOUNTED_P(p)) {
+								Z_ADDREF_P(p);
+							}
+							ZEND_HASH_FILL_ADD(p);
+						}
 						p++;
 						i++;
 					}
@@ -2243,8 +2247,12 @@ static void debug_backtrace_get_args(zend_execute_data *call, zval *arg_array) /
 			}
 
 			while (i < num_args) {
-				if (Z_OPT_REFCOUNTED_P(p)) Z_ADDREF_P(p);
-				ZEND_HASH_FILL_ADD(p);
+				if (Z_TYPE_INFO_P(p) != IS_UNDEF) {
+					if (Z_OPT_REFCOUNTED_P(p)) {
+						Z_ADDREF_P(p);
+					}
+					ZEND_HASH_FILL_ADD(p);
+				}
 				p++;
 				i++;
 			}