diff --git a/insns.def b/insns.def
index 53f9bc0c16..65410e1451 100644
--- a/insns.def
+++ b/insns.def
@@ -365,13 +365,7 @@ concatstrings
 (...)
 (VALUE val) // inc += 1 - num;
 {
-    rb_num_t i = num - 1;
-
-    val = rb_str_resurrect(TOPN(i));
-    while (i-- > 0) {
-	const VALUE v = TOPN(i);
-	rb_str_append_literal(val, v);
-    }
+    val = rb_str_concat_literals(num, &TOPN(num-1));
     POPN(num);
 }
 
diff --git a/string.c b/string.c
index 04d849f136..4ee59b2bd9 100644
--- a/string.c
+++ b/string.c
@@ -2677,13 +2677,24 @@ rb_str_append(VALUE str, VALUE str2)
 }
 
 VALUE
-rb_str_append_literal(VALUE str, VALUE str2)
+rb_str_concat_literals(size_t num, const VALUE *strary)
 {
-    int encidx = rb_enc_get_index(str2);
-    rb_str_buf_append(str, str2);
-    if (encidx != ENCINDEX_US_ASCII) {
-	if (rb_enc_get_index(str) == ENCINDEX_US_ASCII)
-	    rb_enc_associate_index(str, encidx);
+    VALUE str;
+    size_t i;
+
+    if (!num) return rb_str_new(0, 0);
+    str = rb_str_resurrect(strary[0]);
+    for (i = 1; i < num; ++i) {
+	const VALUE v = strary[i];
+	int encidx = ENCODING_GET(v);
+
+	rb_enc_cr_str_buf_cat(str, RSTRING_PTR(v), RSTRING_LEN(v),
+			      encidx, ENC_CODERANGE(v), NULL);
+	OBJ_INFECT_RAW(str, v);
+	if (encidx != ENCINDEX_US_ASCII) {
+	    if (ENCODING_GET_INLINED(str) == ENCINDEX_US_ASCII)
+		rb_enc_set_index(str, encidx);
+	}
     }
     return str;
 }
diff --git a/vm.c b/vm.c
index 64081b49e5..77f57d9839 100644
--- a/vm.c
+++ b/vm.c
@@ -23,7 +23,7 @@
 #include "probes.h"
 #include "probes_helper.h"
 
-VALUE rb_str_append_literal(VALUE str, VALUE str2);
+VALUE rb_str_concat_literals(size_t, const VALUE*);
 
 static inline VALUE *
 VM_EP_LEP(VALUE *ep)