diff --git a/fmt/fmt_strm.3 b/fmt/fmt_strm.3
index 3aa4901..6860f50 100644
--- a/fmt/fmt_strm.3
+++ b/fmt/fmt_strm.3
@@ -17,4 +17,4 @@ If \fIdest\fR equals FMT_LEN (i.e. is zero), fmt_str returns the number
 of bytes it would have written, i.e. the number of leading nonzero bytes
 of \fIsource\fR and following function arguments.
 .SH "SEE ALSO"
-fmt_str(3), strcpy(3)
+fmt_str(3), strcpy(3), fmt_strm_alloca(3), fmt_strm_malloc(3)
diff --git a/fmt/fmt_strm_alloca.3 b/fmt/fmt_strm_alloca.3
new file mode 100644
index 0000000..ffcbc01
--- /dev/null
+++ b/fmt/fmt_strm_alloca.3
@@ -0,0 +1,25 @@
+.TH fmt_strm_alloca 3
+.SH NAME
+fmt_strm_alloca \- write multiple ASCII strings
+.SH SYNTAX
+.B #include <libowfat/fmt.h>
+
+char* \fBfmt_strm_alloca\fP(const char *\fIsource\fR, ...);
+.SH DESCRIPTION
+fmt_strm_alloca copies all leading nonzero bytes from \fIsource\fR and
+following function arguments to a freshly allocated stack buffer and
+returns a pointer to it.
+
+Unlink fmt_strm, fmt_strm_alloca does append \\0.
+
+Warning: Using variable size stack buffers is dangerous. If the size of
+the buffer is larger than the hardware page size, then it can be used to
+skip over the guard page and cause memory corruption. fmt_strm_alloca
+has a built-in limit of 100000 bytes. Use this only for trivially small
+strings.
+
+If the strings do not come from a trusted place or you are not sure they
+are small, prefer fmt_strm_malloc instead.
+
+.SH "SEE ALSO"
+fmt_str(3), fmt_strm(3), fmt_strm_malloc(3), alloca(3), strcpy(3)
diff --git a/fmt/fmt_strm_malloc.3 b/fmt/fmt_strm_malloc.3
new file mode 100644
index 0000000..8966301
--- /dev/null
+++ b/fmt/fmt_strm_malloc.3
@@ -0,0 +1,19 @@
+.TH fmt_strm_malloc 3
+.SH NAME
+fmt_strm_malloc \- write multiple ASCII strings
+.SH SYNTAX
+.B #include <libowfat/fmt.h>
+
+char* \fBfmt_strm_malloc\fP(const char *\fIsource\fR, ...);
+.SH DESCRIPTION
+fmt_strm_malloc copies all leading nonzero bytes from \fIsource\fR and
+following function arguments to a freshly allocated heap buffer and
+returns a pointer to it.
+
+The buffer was allocated with \fImalloc\fR and you need to call
+\fIfree\fR on it when you are done.
+
+Unlink fmt_strm, fmt_strm_malloc does append \\0.
+
+.SH "SEE ALSO"
+fmt_str(3), fmt_strm(3), fmt_strm_alloca(3), alloca(3), strcpy(3)