diff --git a/contrib/eqn2graph/eqn2graph.sh b/contrib/eqn2graph/eqn2graph.sh
index ee7cc5f..c85e06d 100644
--- a/contrib/eqn2graph/eqn2graph.sh
+++ b/contrib/eqn2graph/eqn2graph.sh
@@ -65,7 +65,7 @@ for d in "$GROFF_TMPDIR" "$TMPDIR" "$TMP" "$TEMP" /tmp; do
     && test -n "$tmp" && test -d "$tmp" \
     && break
 
-    tmp=$d/eqn2graph$$-$RANDOM
+    tmp=$d/eqn2graph$$-${RANDOM:-${$}}
     (umask 077 && mkdir $tmp) 2> /dev/null && break
 done;
 if test -z "$tmp"; then
diff --git a/contrib/grap2graph/grap2graph.sh b/contrib/grap2graph/grap2graph.sh
index 58544e1..245e4ca 100644
--- a/contrib/grap2graph/grap2graph.sh
+++ b/contrib/grap2graph/grap2graph.sh
@@ -61,7 +61,7 @@ for d in "$GROFF_TMPDIR" "$TMPDIR" "$TMP" "$TEMP" /tmp; do
     && test -n "$tmp" && test -d "$tmp" \
     && break
 
-    tmp=$d/grap2graph$$-$RANDOM
+    tmp=$d/grap2graph$$-${RANDOM:-${$}}
     (umask 077 && mkdir $tmp) 2> /dev/null && break
 done;
 if test -z "$tmp"; then
diff --git a/contrib/pic2graph/pic2graph.sh b/contrib/pic2graph/pic2graph.sh
index 72c5477..dccd9e7 100644
--- a/contrib/pic2graph/pic2graph.sh
+++ b/contrib/pic2graph/pic2graph.sh
@@ -75,7 +75,7 @@ for d in "$GROFF_TMPDIR" "$TMPDIR" "$TMP" "$TEMP" /tmp; do
     && test -n "$tmp" && test -d "$tmp" \
     && break
 
-    tmp=$d/pic2graph$$-$RANDOM
+    tmp=$d/pic2graph$$-${RANDOM:-${$}}
     (umask 077 && mkdir $tmp) 2> /dev/null \
     && break
 done;