Using rand() in recursive function with linked list

When I run the code, the rand() function seems to generate the same non-random numbers (my intention is to generate random numbers in value). If instead of rand() I use the formal parameter length, it seems that the code works (getting decreased numbers). Where am I doing wrong?

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

struct node{
    int value;
    struct node *next;    
};

struct node *construct(int);

int main(){
    struct node *list = construct( 5 );

    while( list ){
        printf(" %i\n", list->value);
        list = list->next;
    }

    return 0;
}

//It builds a list of "length" items recursively
struct node *construct(int length){
    struct node *node = (struct node *) malloc(sizeof(struct node));

    srand(time(NULL));

    node->value = rand(); /* unclear part of code */

    if( length - 1){
        node->next = construct( length - 1 );
    }

    return node;
}
/* missing the code to free memory */