diff --git a/fmt/fmt_double.c b/fmt/fmt_double.c
index ca7a758..436c431 100644
--- a/fmt/fmt_double.c
+++ b/fmt/fmt_double.c
@@ -16,6 +16,7 @@ unsigned int fmt_double(char *dest, double d,int maxlen,int prec) {
   int writeok=(dest!=0);
 
   if (s) { d=-d; if (writeok) *dest='-'; --maxlen; dest++; }
+  if (d==0.0) { if (writeok) *dest='0'; --maxlen; dest++; return dest-oldbuf; }
   if ((i=e10)>=0) {
     while (i>10) { tmp=tmp*1e10; i-=10; }
     while (i>1) { tmp=tmp*10; --i; }
diff --git a/t.c b/t.c
index c179067..0a38504 100644
--- a/t.c
+++ b/t.c
@@ -12,10 +12,19 @@
      __asm__ __volatile__ ("rdtsc" : "=a" (low) : : "edx")
 
 int main(int argc,char* argv[]) {
-  char buf[100];
+  char buf[100]="01234567890123456789012345678901234567890123456789";
+  long a,b,c;
+#if 0
   buf[ip4_fmt(buf,ip4loopback)]=0;
   buffer_puts(buffer_1small,buf);
   buffer_flush(buffer_1small);
+#endif
+
+  rdtscl(a);
+  c=str_len(buf);
+  rdtscl(b);
+  /*byte_zero_djb(buf,j); */
+  printf("\n%lu %d\n",b-a,c);
 #if 0
   buffer_puts(buffer_1small,"hello, world\n");
   buffer_flush(buffer_1small);