diff --git a/doc/manual/prepro.tex b/doc/manual/prepro.tex
index 34015005..23b87794 100644
--- a/doc/manual/prepro.tex
+++ b/doc/manual/prepro.tex
@@ -87,6 +87,8 @@ \section{The preprocessor variables}
                processes in a job use the same number. A recovered session from
                a checkpoint (\ref{checkpoints}) keeps using the PID of the
                crushed session.
+\item[FORMTMP\_] The path of the FORMTMP directory.
+\item[FORMTMPSORT\_] The path of the FORMTMPSORT directory.
 \item[STOPWATCH\_] Same as `TIMER\_'.
 \item[SYSTEMERROR\_] The return value of the last \#system\ref{presystem}
                command when invoked with the -e\index{SYSTEMERROR\_} option.
diff --git a/sources/startup.c b/sources/startup.c
index 29971b0b..906bb74f 100644
--- a/sources/startup.c
+++ b/sources/startup.c
@@ -654,6 +654,12 @@ VOID ReserveTempFiles(int par)
 			if ( AM.TempSortDir == 0 ) AM.TempSortDir = AM.TempDir;
 		}
 	}
+/*
+	Make these paths available to the user as pre-processor variables:
+*/
+	PutPreVar((UBYTE *)"FORMTMP_", AM.TempDir, 0, 0);
+	PutPreVar((UBYTE *)"FORMTMPSORT_", AM.TempSortDir, 0, 0);
+
 /*
 	We have now in principle a path but we will use its first element only.
 	Later that should become more complicated. Then we will use a path and