diff --git a/ext/ffi/ffi.c b/ext/ffi/ffi.c
index 2000e15c29ea..d823f32127cf 100644
--- a/ext/ffi/ffi.c
+++ b/ext/ffi/ffi.c
@@ -807,6 +807,7 @@ static zend_always_inline zend_result zend_ffi_zval_to_cdata(void *ptr, zend_ffi
 			if (ZSTR_LEN(str) == 1) {
 				*(char*)ptr = ZSTR_VAL(str)[0];
 			} else {
+				zend_tmp_string_release(tmp_str);
 				zend_ffi_assign_incompatible(value, type);
 				return FAILURE;
 			}