diff -Naur a/src/test/regress/pg_regress.c b/src/test/regress/pg_regress.c
--- a/src/test/regress/pg_regress.c	2011-01-27 21:23:36.000000000 -0500
+++ b/src/test/regress/pg_regress.c	2011-03-20 14:19:17.536295541 -0400
@@ -791,7 +791,7 @@
 		datadir = tmp;
 
 		/* psql will be installed into temp-install bindir */
-		psqldir = bindir;
+		/* psqldir = bindir; */
 
 		/*
 		 * Set up shared library paths to include the temp install.
@@ -889,7 +889,7 @@
 
 	/* And now we can build and execute the shell command */
 	snprintf(psql_cmd, sizeof(psql_cmd),
-			 SYSTEMQUOTE "\"%s%spsql\" -X -c \"%s\" \"%s\"" SYSTEMQUOTE,
+			 SYSTEMQUOTE "\"%s%spsql\" -h @SOCKETDIR@ -X -c \"%s\" \"%s\"" SYSTEMQUOTE,
 			 psqldir ? psqldir : "",
 			 psqldir ? "/" : "",
 			 query_escaped,
@@ -2137,8 +2137,8 @@
 		 * Check if there is a postmaster running already.
 		 */
 		snprintf(buf2, sizeof(buf2),
-				 SYSTEMQUOTE "\"%s/psql\" -X postgres <%s 2>%s" SYSTEMQUOTE,
-				 bindir, DEVNULL, DEVNULL);
+				 SYSTEMQUOTE "\"%s/psql\" -h @SOCKETDIR@ -X postgres <%s 2>%s" SYSTEMQUOTE,
+				 psqldir, DEVNULL, DEVNULL);
 
 		for (i = 0; i < 16; i++)
 		{
@@ -2169,7 +2169,7 @@
 		 */
 		header(_("starting postmaster"));
 		snprintf(buf, sizeof(buf),
-				 SYSTEMQUOTE "\"%s/postgres\" -D \"%s/data\" -F%s -c \"listen_addresses=%s\" > \"%s/log/postmaster.log\" 2>&1" SYSTEMQUOTE,
+				 SYSTEMQUOTE "\"%s/postgres\" -k @SOCKETDIR@ -D \"%s/data\" -F%s -c \"listen_addresses=%s\" > \"%s/log/postmaster.log\" 2>&1" SYSTEMQUOTE,
 				 bindir, temp_install,
 				 debug ? " -d 5" : "",
 				 hostname ? hostname : "",
diff -Naur a/src/test/regress/pg_regress_main.c b/src/test/regress/pg_regress_main.c
--- a/src/test/regress/pg_regress_main.c	2011-01-27 21:23:36.000000000 -0500
+++ b/src/test/regress/pg_regress_main.c	2011-03-20 14:20:35.546295541 -0400
@@ -59,7 +59,7 @@
 	add_stringlist_item(expectfiles, expectfile);
 
 	snprintf(psql_cmd, sizeof(psql_cmd),
-			 SYSTEMQUOTE "\"%s%spsql\" -X -a -q -d \"%s\" < \"%s\" > \"%s\" 2>&1" SYSTEMQUOTE,
+			 SYSTEMQUOTE "\"%s%spsql\" -h @SOCKETDIR@ -X -a -q -d \"%s\" < \"%s\" > \"%s\" 2>&1" SYSTEMQUOTE,
 			 psqldir ? psqldir : "",
 			 psqldir ? "/" : "",
 			 dblist->str,