diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index ec14bad4e34..7fe10e284aa 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -1623,8 +1623,8 @@ icu_set_collation_attributes(UCollator *collator, const char *loc)
 		{
 			char	   *name;
 			char	   *value;
-			UColAttribute uattr = -1;
-			UColAttributeValue uvalue = -1;
+			UColAttribute uattr;
+			UColAttributeValue uvalue;
 			UErrorCode	status;
 
 			status = U_ZERO_ERROR;
@@ -1650,7 +1650,9 @@ icu_set_collation_attributes(UCollator *collator, const char *loc)
 				uattr = UCOL_NORMALIZATION_MODE;
 			else if (strcmp(name, "colnumeric") == 0)
 				uattr = UCOL_NUMERIC_COLLATION;
-			/* ignore if unknown */
+			else
+				/* ignore if unknown */
+				continue;
 
 			if (strcmp(value, "primary") == 0)
 				uvalue = UCOL_PRIMARY;
@@ -1677,7 +1679,7 @@ icu_set_collation_attributes(UCollator *collator, const char *loc)
 			else
 				status = U_ILLEGAL_ARGUMENT_ERROR;
 
-			if (uattr != -1 && uvalue != -1)
+			if (status == U_ZERO_ERROR)
 				ucol_setAttribute(collator, uattr, uvalue, &status);
 
 			/*
diff --git a/src/test/regress/expected/collate.icu.utf8.out b/src/test/regress/expected/collate.icu.utf8.out
index 4b94921cf88..b66193d1be2 100644
--- a/src/test/regress/expected/collate.icu.utf8.out
+++ b/src/test/regress/expected/collate.icu.utf8.out
@@ -1101,6 +1101,7 @@ select textrange_en_us('A','Z') @> 'b'::text;
 drop type textrange_c;
 drop type textrange_en_us;
 -- test ICU collation customization
+-- test the attributes handled by icu_set_collation_attributes()
 CREATE COLLATION testcoll_ignore_accents (provider = icu, locale = '@colStrength=primary;colCaseLevel=yes');
 SELECT 'aaá' > 'AAA' COLLATE "und-x-icu", 'aaá' < 'AAA' COLLATE testcoll_ignore_accents;
  ?column? | ?column? 
@@ -1139,6 +1140,15 @@ SELECT 'A-21' > 'A-123' COLLATE "und-x-icu", 'A-21' < 'A-123' COLLATE testcoll_n
 
 CREATE COLLATION testcoll_error1 (provider = icu, locale = '@colNumeric=lower');
 ERROR:  could not open collator for locale "@colNumeric=lower": U_ILLEGAL_ARGUMENT_ERROR
+-- test that attributes not handled by icu_set_collation_attributes()
+-- (handled by ucol_open() directly) also work
+CREATE COLLATION testcoll_de_phonebook (provider = icu, locale = 'de@collation=phonebook');
+SELECT 'Goldmann' < 'Götz' COLLATE "de-x-icu", 'Goldmann' > 'Götz' COLLATE testcoll_de_phonebook;
+ ?column? | ?column? 
+----------+----------
+ t        | t
+(1 row)
+
 -- cleanup
 SET client_min_messages TO warning;
 DROP SCHEMA collate_tests CASCADE;
diff --git a/src/test/regress/sql/collate.icu.utf8.sql b/src/test/regress/sql/collate.icu.utf8.sql
index 73fb1232a7d..68c2d696593 100644
--- a/src/test/regress/sql/collate.icu.utf8.sql
+++ b/src/test/regress/sql/collate.icu.utf8.sql
@@ -427,6 +427,8 @@ drop type textrange_en_us;
 
 -- test ICU collation customization
 
+-- test the attributes handled by icu_set_collation_attributes()
+
 CREATE COLLATION testcoll_ignore_accents (provider = icu, locale = '@colStrength=primary;colCaseLevel=yes');
 SELECT 'aaá' > 'AAA' COLLATE "und-x-icu", 'aaá' < 'AAA' COLLATE testcoll_ignore_accents;
 
@@ -445,6 +447,11 @@ SELECT 'A-21' > 'A-123' COLLATE "und-x-icu", 'A-21' < 'A-123' COLLATE testcoll_n
 
 CREATE COLLATION testcoll_error1 (provider = icu, locale = '@colNumeric=lower');
 
+-- test that attributes not handled by icu_set_collation_attributes()
+-- (handled by ucol_open() directly) also work
+CREATE COLLATION testcoll_de_phonebook (provider = icu, locale = 'de@collation=phonebook');
+SELECT 'Goldmann' < 'Götz' COLLATE "de-x-icu", 'Goldmann' > 'Götz' COLLATE testcoll_de_phonebook;
+
 
 -- cleanup
 SET client_min_messages TO warning;