diff --git a/tests/gen_keys.sh b/tests/gen_keys.sh
index ea82857c..15d29a00 100755
--- a/tests/gen_keys.sh
+++ b/tests/gen_keys.sh
@@ -1,6 +1,7 @@
 #!/bin/sh
 
 set -e
+set -u
 
 # Generate test keys
 
diff --git a/tests/mansyntax.sh b/tests/mansyntax.sh
index 2f3d3e81..6991f473 100755
--- a/tests/mansyntax.sh
+++ b/tests/mansyntax.sh
@@ -1,6 +1,7 @@
 #!/bin/sh
 
 set -e
+set -u
 
 # Written by Mikhail Gusarov
 #
diff --git a/tests/test_read_algos.test b/tests/test_read_algos.test
index b5c5a9c7..1616b5d8 100755
--- a/tests/test_read_algos.test
+++ b/tests/test_read_algos.test
@@ -1,5 +1,8 @@
 #!/usr/bin/env bash
 
+set -e
+set -u
+
 # https://testanything.org/tap-specification.html
 
 if [[ "$(uname)" = *'_NT'* ]]; then
@@ -8,7 +11,7 @@ if [[ "$(uname)" = *'_NT'* ]]; then
   exit 0
 fi
 
-testbin="./test_read${EXEEXT}"
+testbin="./test_read${EXEEXT:-}"
 
 d="$(dirname "$0")"
 algos="$(tr -d $"\r" < "${d}/test_read_algos.txt")"
diff --git a/tests/test_sshd.test b/tests/test_sshd.test
index 03ca3d75..de13dfa5 100755
--- a/tests/test_sshd.test
+++ b/tests/test_sshd.test
@@ -1,5 +1,8 @@
 #!/usr/bin/env bash
 
+set -e
+set -u
+
 # https://testanything.org/tap-specification.html
 
 d="$(dirname "$0")"
@@ -25,7 +28,7 @@ total="$(echo "${tests}" | wc -w | tr -d ' ')"
 echo "${count}..${total}"
 
 for test in ${tests}; do
-  if "${d}/sshd_fixture.sh" "./${test}${EXEEXT}"; then
+  if "${d}/sshd_fixture.sh" "./${test}${EXEEXT:-}"; then
     res='ok'
   else
     res='not ok'