diff --git a/prism/prism.c b/prism/prism.c
index 45817cdd8c05b2..186cdd354c9843 100644
--- a/prism/prism.c
+++ b/prism/prism.c
@@ -13849,6 +13849,18 @@ parse_write(pm_parser_t *parser, pm_node_t *target, pm_token_t *operator, pm_nod
             // syntax error. In this case we'll fall through to our default
             // handling. We need to free the value that we parsed because there
             // is no way for us to attach it to the tree at this point.
+            switch (PM_NODE_TYPE(value)) {
+                case PM_LOCAL_VARIABLE_READ_NODE:
+                case PM_IT_LOCAL_VARIABLE_READ_NODE:
+                    // Since it is possible for the value to be an implicit
+                    // parameter, we need to remove it from the list of implicit
+                    // parameters.
+                    parse_target_implicit_parameter(parser, value);
+                    break;
+                default:
+                    break;
+            }
+
             pm_node_destroy(parser, value);
         }
         PRISM_FALLTHROUGH
@@ -22620,7 +22632,7 @@ static const char *
 pm_strnstr(const char *big, const char *little, size_t big_length) {
     size_t little_length = strlen(little);
 
-    for (const char *big_end = big + big_length; big < big_end; big++) {
+    for (const char *max = big + big_length - little_length; big <= max; big++) {
         if (*big == *little && memcmp(big, little, little_length) == 0) return big;
     }
 
diff --git a/process.c b/process.c
index 46c55abcce42c6..8d6953282aaa41 100644
--- a/process.c
+++ b/process.c
@@ -4011,7 +4011,10 @@ retry_fork_async_signal_safe(struct rb_process_status *status, int *ep,
     while (1) {
         prefork();
         disable_child_handler_before_fork(&old);
-#ifdef HAVE_WORKING_VFORK
+
+    // Older versions of ASAN does not work with vfork
+    // See https://github.com/google/sanitizers/issues/925
+#if defined(HAVE_WORKING_VFORK) && !defined(RUBY_ASAN_ENABLED)
         if (!has_privilege())
             pid = vfork();
         else