diff --git a/src/test/modules/test_regex/expected/test_regex_utf8.out b/src/test/modules/test_regex/expected/test_regex_utf8.out
index 329780ef400..177eb1cacec 100644
--- a/src/test/modules/test_regex/expected/test_regex_utf8.out
+++ b/src/test/modules/test_regex/expected/test_regex_utf8.out
@@ -147,7 +147,9 @@ select * from test_regex('[[:digit:]]+',  E'x9\u1500\u1237', 'L');
  {9}
 (2 rows)
 
-select * from test_regex('[[:graph:]]+',  E'x\u1500\u1237', 'L');
+-- graph and print depend on the ctype and not just the encoding, so pin them
+-- to a Unicode-aware collation rather than the database's
+select * from test_regex('[[:graph:]]+',  E'x\u1500\u1237' COLLATE pg_c_utf8, 'L');
    test_regex    
 -----------------
  {0,REG_ULOCALE}
@@ -161,7 +163,7 @@ select * from test_regex('[[:lower:]]+',  E'x\u1500\u1237', 'L');
  {x}
 (2 rows)
 
-select * from test_regex('[[:print:]]+',  E'x\u1500\u1237', 'L');
+select * from test_regex('[[:print:]]+',  E'x\u1500\u1237' COLLATE pg_c_utf8, 'L');
    test_regex    
 -----------------
  {0,REG_ULOCALE}
diff --git a/src/test/modules/test_regex/sql/test_regex_utf8.sql b/src/test/modules/test_regex/sql/test_regex_utf8.sql
index 1f69f105fd7..d00599b3490 100644
--- a/src/test/modules/test_regex/sql/test_regex_utf8.sql
+++ b/src/test/modules/test_regex/sql/test_regex_utf8.sql
@@ -66,9 +66,11 @@ select * from test_regex('[[:ascii:]]+',  E'x\u1500\u1237', 'L');
 select * from test_regex('[[:blank:]]+',  E'x \t\u1500\u1237', 'L');
 select * from test_regex('[[:cntrl:]]+',  E'x\u1500\u1237', 'L');
 select * from test_regex('[[:digit:]]+',  E'x9\u1500\u1237', 'L');
-select * from test_regex('[[:graph:]]+',  E'x\u1500\u1237', 'L');
+-- graph and print depend on the ctype and not just the encoding, so pin them
+-- to a Unicode-aware collation rather than the database's
+select * from test_regex('[[:graph:]]+',  E'x\u1500\u1237' COLLATE pg_c_utf8, 'L');
 select * from test_regex('[[:lower:]]+',  E'x\u1500\u1237', 'L');
-select * from test_regex('[[:print:]]+',  E'x\u1500\u1237', 'L');
+select * from test_regex('[[:print:]]+',  E'x\u1500\u1237' COLLATE pg_c_utf8, 'L');
 select * from test_regex('[[:punct:]]+',  E'x.\u1500\u1237', 'L');
 select * from test_regex('[[:space:]]+',  E'x \t\u1500\u1237', 'L');
 select * from test_regex('[[:upper:]]+',  E'xX\u1500\u1237', 'L');