diff --git a/compile.c b/compile.c
index 9e9e177231..797e983816 100644
--- a/compile.c
+++ b/compile.c
@@ -5177,6 +5177,7 @@ iseq_compile_each(rb_iseq_t *iseq, LINK_ANCHOR *const ret, NODE *node, int poppe
 	    nd_type(node->nd_args) == NODE_ARRAY && node->nd_args->nd_alen == 1 &&
 	    nd_type(node->nd_args->nd_head) == NODE_STR &&
 	    ISEQ_COMPILE_DATA(iseq)->current_block == NULL &&
+            !ISEQ_COMPILE_DATA(iseq)->option->frozen_string_literal &&
 	    ISEQ_COMPILE_DATA(iseq)->option->specialized_instruction) {
 	    VALUE str = rb_fstring(node->nd_args->nd_head->nd_lit);
 	    node->nd_args->nd_head->nd_lit = str;
@@ -6229,6 +6230,7 @@ iseq_compile_each(rb_iseq_t *iseq, LINK_ANCHOR *const ret, NODE *node, int poppe
 	    nd_type(node->nd_args) == NODE_ARRAY && node->nd_args->nd_alen == 2 &&
 	    nd_type(node->nd_args->nd_head) == NODE_STR &&
 	    ISEQ_COMPILE_DATA(iseq)->current_block == NULL &&
+            !ISEQ_COMPILE_DATA(iseq)->option->frozen_string_literal &&
 	    ISEQ_COMPILE_DATA(iseq)->option->specialized_instruction)
 	{
 	    VALUE str = rb_fstring(node->nd_args->nd_head->nd_lit);
diff --git a/version.h b/version.h
index bc6c7df75c..a4306172c5 100644
--- a/version.h
+++ b/version.h
@@ -1,6 +1,6 @@
 #define RUBY_VERSION "2.4.5"
 #define RUBY_RELEASE_DATE "2018-10-17"
-#define RUBY_PATCHLEVEL 330
+#define RUBY_PATCHLEVEL 331
 
 #define RUBY_RELEASE_YEAR 2018
 #define RUBY_RELEASE_MONTH 10