diff --git a/src/test/ssl/t/001_ssltests.pl b/src/test/ssl/t/001_ssltests.pl
index 67a3a28db6..d3896f7946 100644
--- a/src/test/ssl/t/001_ssltests.pl
+++ b/src/test/ssl/t/001_ssltests.pl
@@ -97,8 +97,13 @@ note "running client tests";
 
 switch_server_cert($node, 'server-cn-only');
 
+# Set of default settings for SSL parameters in connection string.  This
+# makes the tests protected against any defaults the environment may have
+# in ~/.postgresql/.
+my $default_ssl_connstr = "sslkey=invalid sslcert=invalid sslrootcert=invalid sslcrl=invalid";
+
 $common_connstr =
-  "user=ssltestuser dbname=trustdb sslcert=invalid hostaddr=$SERVERHOSTADDR host=common-name.pg-ssltest.test";
+  "$default_ssl_connstr user=ssltestuser dbname=trustdb hostaddr=$SERVERHOSTADDR host=common-name.pg-ssltest.test";
 
 # The server should not accept non-SSL connections.
 test_connect_fails(
@@ -190,7 +195,7 @@ test_connect_ok(
 # Check that connecting with verify-full fails, when the hostname doesn't
 # match the hostname in the server's certificate.
 $common_connstr =
-  "user=ssltestuser dbname=trustdb sslcert=invalid sslrootcert=ssl/root+server_ca.crt hostaddr=$SERVERHOSTADDR";
+  "$default_ssl_connstr user=ssltestuser dbname=trustdb sslrootcert=ssl/root+server_ca.crt hostaddr=$SERVERHOSTADDR";
 
 test_connect_ok(
 	$common_connstr,
@@ -210,7 +215,7 @@ test_connect_fails(
 switch_server_cert($node, 'server-multiple-alt-names');
 
 $common_connstr =
-  "user=ssltestuser dbname=trustdb sslcert=invalid sslrootcert=ssl/root+server_ca.crt hostaddr=$SERVERHOSTADDR sslmode=verify-full";
+  "$default_ssl_connstr user=ssltestuser dbname=trustdb sslrootcert=ssl/root+server_ca.crt hostaddr=$SERVERHOSTADDR sslmode=verify-full";
 
 test_connect_ok(
 	$common_connstr,
@@ -241,7 +246,7 @@ test_connect_fails(
 switch_server_cert($node, 'server-single-alt-name');
 
 $common_connstr =
-  "user=ssltestuser dbname=trustdb sslcert=invalid sslrootcert=ssl/root+server_ca.crt hostaddr=$SERVERHOSTADDR sslmode=verify-full";
+  "$default_ssl_connstr user=ssltestuser dbname=trustdb sslrootcert=ssl/root+server_ca.crt hostaddr=$SERVERHOSTADDR sslmode=verify-full";
 
 test_connect_ok(
 	$common_connstr,
@@ -265,7 +270,7 @@ test_connect_fails(
 switch_server_cert($node, 'server-cn-and-alt-names');
 
 $common_connstr =
-  "user=ssltestuser dbname=trustdb sslcert=invalid sslrootcert=ssl/root+server_ca.crt hostaddr=$SERVERHOSTADDR sslmode=verify-full";
+  "$default_ssl_connstr user=ssltestuser dbname=trustdb sslrootcert=ssl/root+server_ca.crt hostaddr=$SERVERHOSTADDR sslmode=verify-full";
 
 test_connect_ok(
 	$common_connstr,
@@ -285,7 +290,7 @@ test_connect_fails(
 # not a very sensible certificate, but libpq should handle it gracefully.
 switch_server_cert($node, 'server-no-names');
 $common_connstr =
-  "user=ssltestuser dbname=trustdb sslcert=invalid sslrootcert=ssl/root+server_ca.crt hostaddr=$SERVERHOSTADDR";
+  "$default_ssl_connstr user=ssltestuser dbname=trustdb sslrootcert=ssl/root+server_ca.crt hostaddr=$SERVERHOSTADDR";
 
 test_connect_ok(
 	$common_connstr,
@@ -301,7 +306,7 @@ test_connect_fails(
 switch_server_cert($node, 'server-revoked');
 
 $common_connstr =
-  "user=ssltestuser dbname=trustdb sslcert=invalid hostaddr=$SERVERHOSTADDR host=common-name.pg-ssltest.test";
+  "$default_ssl_connstr user=ssltestuser dbname=trustdb hostaddr=$SERVERHOSTADDR host=common-name.pg-ssltest.test";
 
 # Without the CRL, succeeds. With it, fails.
 test_connect_ok(
@@ -335,7 +340,7 @@ command_like(
 note "running server tests";
 
 $common_connstr =
-  "sslrootcert=ssl/root+server_ca.crt sslmode=require dbname=certdb hostaddr=$SERVERHOSTADDR";
+  "$default_ssl_connstr sslrootcert=ssl/root+server_ca.crt sslmode=require dbname=certdb hostaddr=$SERVERHOSTADDR";
 
 # no client cert
 test_connect_fails(
@@ -400,7 +405,7 @@ test_connect_fails(
 # works, iff username matches Common Name
 # fails, iff username doesn't match Common Name.
 $common_connstr =
-  "sslrootcert=ssl/root+server_ca.crt sslmode=require dbname=verifydb hostaddr=$SERVERHOSTADDR";
+  "$default_ssl_connstr sslrootcert=ssl/root+server_ca.crt sslmode=require dbname=verifydb hostaddr=$SERVERHOSTADDR";
 
 test_connect_ok(
 	$common_connstr,
@@ -426,7 +431,7 @@ test_connect_ok(
 # intermediate client_ca.crt is provided by client, and isn't in server's ssl_ca_file
 switch_server_cert($node, 'server-cn-only', 'root_ca');
 $common_connstr =
-  "user=ssltestuser dbname=certdb sslkey=ssl/client_tmp.key sslrootcert=ssl/root+server_ca.crt hostaddr=$SERVERHOSTADDR";
+  "$default_ssl_connstr user=ssltestuser dbname=certdb sslkey=ssl/client_tmp.key sslrootcert=ssl/root+server_ca.crt hostaddr=$SERVERHOSTADDR";
 
 test_connect_ok(
 	$common_connstr,