diff --git a/string.c b/string.c
index 28b1efa2e9..227424d266 100644
--- a/string.c
+++ b/string.c
@@ -2090,9 +2090,7 @@ rb_enc_cr_str_buf_cat(VALUE str, const char *ptr, long len,
     str_cr = RSTRING_LEN(str) ? ENC_CODERANGE(str) : ENC_CODERANGE_7BIT;
 
     if (str_encindex == ptr_encindex) {
-        if (str_cr == ENC_CODERANGE_UNKNOWN)
-            ptr_cr = ENC_CODERANGE_UNKNOWN;
-        else if (ptr_cr == ENC_CODERANGE_UNKNOWN) {
+	if (str_cr != ENC_CODERANGE_UNKNOWN && ptr_cr == ENC_CODERANGE_UNKNOWN) {
             ptr_cr = coderange_scan(ptr, len, rb_enc_from_index(ptr_encindex));
         }
     }