Smallest Palindrome from a String, attempt2

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

int isPalin ( char *str ) {
    int i, len=strlen(str);
    for (i=0; i<len/2; ++i)
        if (str[i]!=str[len-i-1])
            break;
    return i==len/2;
}

int main(int argc, char *argv[]) {
    if (argc!=2)
        puts("Usage: small_palin <string>");
    else {
        char *str = argv[1];
        int i=0, j, len=strlen(str);
        while ( !isPalin(str+i) )
            ++i;
        char *palin = malloc(len+1+i);
        *(palin+len+1+i) = '\0';
        strcpy(palin,str);
        for (i=i-1, j=0; i>=0; --i, ++j)
            *(palin+len+j) = str[i];
        puts(palin);
    }
    return 0;
}