diff --git a/CHANGES b/CHANGES
index 3c49c0e..78a4058 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,4 +1,5 @@
 0.27:
+  add fmt_strm
 
 0.26:
   fix really pathological case where io_timeouted would never
diff --git a/fmt.h b/fmt.h
index 2be0f90..458b34a 100644
--- a/fmt.h
+++ b/fmt.h
@@ -90,4 +90,7 @@ size_t fmt_httpdate(char* dest,time_t t);
 /* internal functions, may be independently useful */
 char fmt_tohex(char c);
 
+#define fmt_strm(b,...) fmt_strm_internal(b,__VA_ARGS__,(char*)0)
+size_t fmt_strm_internal(char* dest,...);
+
 #endif
diff --git a/fmt/fmt_strm_internal.c b/fmt/fmt_strm_internal.c
new file mode 100644
index 0000000..75dcbfb
--- /dev/null
+++ b/fmt/fmt_strm_internal.c
@@ -0,0 +1,17 @@
+#include <stdarg.h>
+#include "fmt.h"
+
+size_t fmt_strm_internal(char* dest, ...) {
+  size_t n;
+  va_list a;
+  const char* s;
+  va_start(a,dest);
+  for (n=0; s=va_arg(a,const char*); ) {
+    size_t inc=fmt_str(dest,s);
+    if (n+inc<n) return (size_t)-1;
+    if (dest) dest+=inc;
+    n+=inc;
+  }
+  va_end(a);
+  return n;
+}
diff --git a/test/fmt.c b/test/fmt.c
new file mode 100644
index 0000000..cd11c4c
--- /dev/null
+++ b/test/fmt.c
@@ -0,0 +1,14 @@
+#include <fmt.h>
+#include <string.h>
+#include <assert.h>
+
+int main() {
+  char buf[100];
+  buf[5]='x';
+  assert(fmt_str(buf,"fnord")==5);
+  assert(buf[5]=='x');
+  buf[5]=0;
+  assert(!strcmp(buf,"fnord"));
+  assert(fmt_strm(buf,"Fn","0rd")==5);
+  assert(!strcmp(buf,"Fn0rd"));
+}