diff --git a/src/njs_string.c b/src/njs_string.c
index 6d7c464dc..cf3e13937 100644
--- a/src/njs_string.c
+++ b/src/njs_string.c
@@ -601,10 +601,11 @@ njs_int_t
 njs_string_prototype_concat(njs_vm_t *vm, njs_value_t *args, njs_uint_t nargs,
     njs_index_t unused, njs_value_t *retval)
 {
+    double             num;
     u_char             *p, *start;
     uint64_t           size, length, mask;
     njs_int_t          ret;
-    njs_uint_t         i;
+    njs_uint_t         i, i_buf, n_bufs;
     njs_string_prop_t  string;
 
     if (njs_is_null_or_undefined(&args[0])) {
@@ -612,8 +613,44 @@ njs_string_prototype_concat(njs_vm_t *vm, njs_value_t *args, njs_uint_t nargs,
         return NJS_ERROR;
     }
 
+    n_bufs = njs_min(nargs,16);
+
+    u_char        buf[n_bufs][32];
+    njs_string_t  sp[n_bufs];
+
+    i_buf = 0;
+
     for (i = 0; i < nargs; i++) {
-        if (!njs_is_string(&args[i])) {
+        if (i_buf < n_bufs && njs_is_number(&args[i])) {
+            num = njs_number(&args[i]);
+
+            if (isnan(num)) {
+                njs_atom_to_value(vm, &args[i], NJS_ATOM_STRING_NaN);
+
+            } else if (isinf(num)) {
+
+                if (num < 0) {
+                    njs_atom_to_value(vm, &args[i], NJS_ATOM_STRING__Infinity);
+
+                } else {
+                    njs_atom_to_value(vm, &args[i], NJS_ATOM_STRING_Infinity);
+                }
+
+            } else {
+                size = njs_dtoa(num, (char *) buf[i]);
+
+                sp[i_buf].start = (u_char *)buf[i];
+                sp[i_buf].length = sp[i_buf].size = size;
+
+                args[i].type = NJS_STRING;
+                args[i].truth = size != 0;
+                args[i].atom_id = NJS_ATOM_STRING_unknown;
+                args[i].string.data = &sp[i_buf];
+
+                i_buf++;
+            }
+
+        } if (!njs_is_string(&args[i])) {
             ret = njs_value_to_string(vm, &args[i], &args[i]);
             if (ret != NJS_OK) {
                 return ret;
diff --git a/src/njs_vmcode.c b/src/njs_vmcode.c
index c7adf63f7..3b7993ce7 100644
--- a/src/njs_vmcode.c
+++ b/src/njs_vmcode.c
@@ -667,14 +667,52 @@ NEXT_LBL;
             src = value1;
         }
 
-        ret = njs_primitive_value_to_string(vm, &dst, src);
-        if (njs_slow_path(ret != NJS_OK)) {
-            goto error;
-        }
+        if (src->type == NJS_NUMBER) {
 
-        ret = njs_string_concat(vm, s1, s2, &name);
-        if (njs_slow_path(ret == NJS_ERROR)) {
-            goto error;
+            double  num;
+            size_t  size;
+            u_char  buf[32];
+
+            njs_string_t sp;
+
+            num = njs_number(src);
+
+            if (isnan(num)) {
+                njs_atom_to_value(vm, &dst, NJS_ATOM_STRING_NaN);
+
+            } else if (isinf(num)) {
+
+                if (num < 0) {
+                    njs_atom_to_value(vm, &dst, NJS_ATOM_STRING__Infinity);
+
+                } else {
+                    njs_atom_to_value(vm, &dst, NJS_ATOM_STRING_Infinity);
+                }
+
+            } else {
+                size = njs_dtoa(num, (char *) buf);
+
+                sp.start = (u_char *)buf;
+                sp.length = sp.size = size;
+
+                dst.string.data = &sp;
+            }
+
+            ret = njs_string_concat(vm, s1, s2, &name);
+            if (njs_slow_path(ret == NJS_ERROR)) {
+                goto error;
+            }
+
+        } else {
+            ret = njs_primitive_value_to_string(vm, &dst, src);
+            if (njs_slow_path(ret != NJS_OK)) {
+                goto error;
+            }
+
+            ret = njs_string_concat(vm, s1, s2, &name);
+            if (njs_slow_path(ret == NJS_ERROR)) {
+                goto error;
+            }
         }
 
         njs_value_assign(retval, &name);
@@ -2010,6 +2048,8 @@ njs_vmcode_template_literal(njs_vm_t *vm, njs_value_t *retval)
         return ret;
     }
 
+    njs_array_destroy(vm, array);
+
     return sizeof(njs_vmcode_template_literal_t);
 }