you need to #include <stdlib.h>

fmt/fmt_strm_malloc.3

@@ -2,6 +2,7 @@
 .SH NAME
 fmt_strm_malloc \- write multiple ASCII strings
 .SH SYNTAX
+.B #include <stdlib.h>
 .B #include <libowfat/fmt.h>
 
 char* \fBfmt_strm_malloc\fP(const char *\fIsource\fR, ...);