diff --git a/Zend/tests/compound_assign_failure.phpt b/Zend/tests/compound_assign_failure.phpt
new file mode 100644
index 00000000000..f1afc783a0e
--- /dev/null
+++ b/Zend/tests/compound_assign_failure.phpt
@@ -0,0 +1,24 @@
+--TEST--
+Behavior of failing compound assignment
+--FILE--
+<?php
+
+try {
+	$a = 1;
+	$a %= 0;
+} catch (Error $e) { var_dump($a); }
+
+try {
+	$a = 1;
+	$a >>= -1;
+} catch (Error $e) { var_dump($a); }
+
+try {
+	$a = 1;
+	$a <<= -1;
+} catch (Error $e) { var_dump($a); }
+?>
+--EXPECT--
+int(1)
+int(1)
+int(1)
diff --git a/Zend/zend_operators.c b/Zend/zend_operators.c
index de0c19e94f1..d5d42ca1e14 100644
--- a/Zend/zend_operators.c
+++ b/Zend/zend_operators.c
@@ -1182,10 +1182,6 @@ ZEND_API int ZEND_FASTCALL mod_function(zval *result, zval *op1, zval *op2) /* {
 
 	convert_op1_op2_long(op1, op1_lval, op2, op2_lval, ZEND_MOD, mod_function);
 
-	if (op1 == result) {
-		zval_dtor(result);
-	}
-
 	if (op2_lval == 0) {
 		/* modulus by zero */
 		if (EG(current_execute_data) && !CG(in_compilation)) {
@@ -1193,10 +1189,16 @@ ZEND_API int ZEND_FASTCALL mod_function(zval *result, zval *op1, zval *op2) /* {
 		} else {
 			zend_error_noreturn(E_ERROR, "Modulo by zero");
 		}
-		ZVAL_UNDEF(result);
+		if (op1 != result) {
+			ZVAL_UNDEF(result);
+		}
 		return FAILURE;
 	}
 
+	if (op1 == result) {
+		zval_dtor(result);
+	}
+
 	if (op2_lval == -1) {
 		/* Prevent overflow error/crash if op1==LONG_MIN */
 		ZVAL_LONG(result, 0);
@@ -1540,13 +1542,12 @@ ZEND_API int ZEND_FASTCALL shift_left_function(zval *result, zval *op1, zval *op
 
 	convert_op1_op2_long(op1, op1_lval, op2, op2_lval, ZEND_SL, shift_left_function);
 
-	if (op1 == result) {
-		zval_dtor(result);
-	}
-
 	/* prevent wrapping quirkiness on some processors where << 64 + x == << x */
 	if (UNEXPECTED((zend_ulong)op2_lval >= SIZEOF_ZEND_LONG * 8)) {
 		if (EXPECTED(op2_lval > 0)) {
+			if (op1 == result) {
+				zval_dtor(result);
+			}
 			ZVAL_LONG(result, 0);
 			return SUCCESS;
 		} else {
@@ -1555,11 +1556,17 @@ ZEND_API int ZEND_FASTCALL shift_left_function(zval *result, zval *op1, zval *op
 			} else {
 				zend_error_noreturn(E_ERROR, "Bit shift by negative number");
 			}
-			ZVAL_UNDEF(result);
+			if (op1 != result) {
+				ZVAL_UNDEF(result);
+			}
 			return FAILURE;
 		}
 	}
 
+	if (op1 == result) {
+		zval_dtor(result);
+	}
+
 	ZVAL_LONG(result, op1_lval << op2_lval);
 	return SUCCESS;
 }
@@ -1571,14 +1578,13 @@ ZEND_API int ZEND_FASTCALL shift_right_function(zval *result, zval *op1, zval *o
 
 	convert_op1_op2_long(op1, op1_lval, op2, op2_lval, ZEND_SR, shift_right_function);
 
-	if (op1 == result) {
-		zval_dtor(result);
-	}
-
 	/* prevent wrapping quirkiness on some processors where >> 64 + x == >> x */
 	if (UNEXPECTED((zend_ulong)op2_lval >= SIZEOF_ZEND_LONG * 8)) {
 		if (EXPECTED(op2_lval > 0)) {
 			ZVAL_LONG(result, (op1_lval < 0) ? -1 : 0);
+			if (op1 == result) {
+				zval_dtor(result);
+			}
 			return SUCCESS;
 		} else {
 			if (EG(current_execute_data) && !CG(in_compilation)) {
@@ -1586,11 +1592,17 @@ ZEND_API int ZEND_FASTCALL shift_right_function(zval *result, zval *op1, zval *o
 			} else {
 				zend_error_noreturn(E_ERROR, "Bit shift by negative number");
 			}
-			ZVAL_UNDEF(result);
+			if (op1 != result) {
+				ZVAL_UNDEF(result);
+			}
 			return FAILURE;
 		}
 	}
 
+	if (op1 == result) {
+		zval_dtor(result);
+	}
+
 	ZVAL_LONG(result, op1_lval >> op2_lval);
 	return SUCCESS;
 }
@@ -1598,6 +1610,7 @@ ZEND_API int ZEND_FASTCALL shift_right_function(zval *result, zval *op1, zval *o
 
 ZEND_API int ZEND_FASTCALL concat_function(zval *result, zval *op1, zval *op2) /* {{{ */
 {
+    zval *orig_op1 = op1;
 	zval op1_copy, op2_copy;
 	int use_copy1 = 0, use_copy2 = 0;
 
@@ -1610,11 +1623,7 @@ ZEND_API int ZEND_FASTCALL concat_function(zval *result, zval *op1, zval *op2) /
 			ZEND_TRY_BINARY_OBJECT_OPERATION(ZEND_CONCAT, concat_function);
 			use_copy1 = zend_make_printable_zval(op1, &op1_copy);
 			if (use_copy1) {
-				/* We have created a converted copy of op1. Therefore, op1 won't become the result so
-				 * we have to free it.
-				 */
 				if (result == op1) {
-					zval_dtor(op1);
 					if (UNEXPECTED(op1 == op2)) {
 						op2 = &op1_copy;
 					}
@@ -1645,7 +1654,15 @@ ZEND_API int ZEND_FASTCALL concat_function(zval *result, zval *op1, zval *op2) /
 
 		if (UNEXPECTED(op1_len > SIZE_MAX - op2_len)) {
 			zend_throw_error(NULL, "String size overflow");
-			ZVAL_FALSE(result);
+			if (UNEXPECTED(use_copy1)) {
+				zval_dtor(op1);
+			}
+			if (UNEXPECTED(use_copy2)) {
+				zval_dtor(op2);
+			}
+			if (orig_op1 != result) {
+				ZVAL_UNDEF(result);
+			}
 			return FAILURE;
 		}
 
@@ -1655,6 +1672,9 @@ ZEND_API int ZEND_FASTCALL concat_function(zval *result, zval *op1, zval *op2) /
 		} else {
 			result_str = zend_string_alloc(result_len, 0);
 			memcpy(ZSTR_VAL(result_str), Z_STRVAL_P(op1), op1_len);
+			if (result == orig_op1) {
+				zval_dtor(orig_op1);
+			}
 		}
 
 		/* This has to happen first to account for the cases where result == op1 == op2 and