diff --git a/tests/ctlseqs/match.exp b/tests/ctlseqs/match.exp
index 239c143..aedcf51 100644
--- a/tests/ctlseqs/match.exp
+++ b/tests/ctlseqs/match.exp
@@ -9,9 +9,9 @@
 set tool ctlseqs
 set timeout 2
 
-set n1 [ expr int(rand()*5000) ]
-set n2 [ expr int(rand()*5000) ]
-set n3 [ expr int(rand()*5000) ]
+set n1 [ random_int ]
+set n2 [ random_int ]
+set n3 [ random_int ]
 
 set input { }
 lappend input "$CSI$n1;${n2}H"
diff --git a/tests/init.exp b/tests/init.exp
index b3c1d1e..a047423 100644
--- a/tests/init.exp
+++ b/tests/init.exp
@@ -6,6 +6,11 @@
 # this notice are preserved. This file is offered as-is, without any warranty.
 # 
 
+set ESC "\x1b"
+set CSI "$ESC\["
+set DCS "${ESC}P"
+set ST  "$ESC\\"
+
 proc tcsgrep_start args {
     global TCSGREP_BIN
     set run_cmd [ list $TCSGREP_BIN "-t500" ]
@@ -38,7 +43,7 @@ proc tcsgrep_stop { } {
     }
 }
 
-set ESC "\x1b"
-set CSI "$ESC\["
-set DCS "${ESC}P"
-set ST  "$ESC\\"
+proc random_int { } {
+    set num [ exec od -An -td -N4 /dev/urandom ]
+    return [ expr abs(int($num)) ]
+}