diff --git a/src/box/sql/func.c b/src/box/sql/func.c
index e211de114146142a053c876823af13f1c5570db7..45056a7da57e288af21bfc39b3dd0a512fbfe9af 100644
--- a/src/box/sql/func.c
+++ b/src/box/sql/func.c
@@ -37,12 +37,13 @@
 #include "sqliteInt.h"
 #include "vdbeInt.h"
 #include "version.h"
+#include "coll.h"
 #include <unicode/ustring.h>
 #include <unicode/ucasemap.h>
 #include <unicode/ucnv.h>
 #include <unicode/uchar.h>
+#include <unicode/ucol.h>
 
-static UCaseMap *pUCaseMap;
 static UConverter* pUtf8conv;
 
 /*
@@ -503,7 +504,15 @@ case_type##ICUFunc(sqlite3_context *context, int argc, sqlite3_value **argv)   \
 		return;                                                        \
 	}                                                                      \
 	UErrorCode status = U_ZERO_ERROR;                                      \
-	int len = ucasemap_utf8To##case_type(pUCaseMap, z1, n, z2, n, &status);\
+	struct coll *coll = sqlite3GetFuncCollSeq(context);                    \
+	const char *locale = NULL;                                             \
+	if (coll != NULL) {                                                    \
+		locale = ucol_getLocaleByType(coll->collator,                  \
+					      ULOC_VALID_LOCALE, &status);     \
+	}                                                                      \
+	UCaseMap *case_map = ucasemap_open(locale, 0, &status);                \
+	assert(case_map != NULL);                                              \
+	int len = ucasemap_utf8To##case_type(case_map, z1, n, z2, n, &status); \
 	if (len > n) {                                                         \
 		status = U_ZERO_ERROR;                                         \
 		sqlite3_free(z1);                                              \
@@ -512,8 +521,9 @@ case_type##ICUFunc(sqlite3_context *context, int argc, sqlite3_value **argv)   \
 			sqlite3_result_error_nomem(context);                   \
 			return;                                                \
 		}                                                              \
-		ucasemap_utf8To##case_type(pUCaseMap, z1, len, z2, n, &status);\
+		ucasemap_utf8To##case_type(case_map, z1, len, z2, n, &status); \
 	}                                                                      \
+	ucasemap_close(case_map);                                              \
 	sqlite3_result_text(context, z1, len, sqlite3_free);                   \
 }                                                                              \
 
@@ -1789,8 +1799,6 @@ sqlite3RegisterBuiltinFunctions(void)
 	 */
 	UErrorCode status = U_ZERO_ERROR;
 
-	pUCaseMap = ucasemap_open(NULL, 0, &status);
-	assert(pUCaseMap);
 	pUtf8conv = ucnv_open("utf8", &status);
 	assert(pUtf8conv);
 	/*
@@ -1835,8 +1843,8 @@ sqlite3RegisterBuiltinFunctions(void)
 		FUNCTION(round, 1, 0, 0, roundFunc),
 		FUNCTION(round, 2, 0, 0, roundFunc),
 #endif
-		FUNCTION(upper, 1, 0, 0, UpperICUFunc),
-		FUNCTION(lower, 1, 0, 0, LowerICUFunc),
+		FUNCTION(upper, 1, 0, 1, UpperICUFunc),
+		FUNCTION(lower, 1, 0, 1, LowerICUFunc),
 		FUNCTION(hex, 1, 0, 0, hexFunc),
 		FUNCTION2(ifnull, 2, 0, 0, noopFunc, SQLITE_FUNC_COALESCE),
 		VFUNCTION(random, 0, 0, 0, randomFunc),
diff --git a/test/sql/collation.result b/test/sql/collation.result
index 7fec96d51b7294a691e2dc37b36896c9947315b6..79ba9abc0f093fc005bb27fe18b3eb5902bf9398 100644
--- a/test/sql/collation.result
+++ b/test/sql/collation.result
@@ -32,6 +32,68 @@ box.sql.execute("SELECT 1 LIMIT 1 COLLATE BINARY, 1;")
 ---
 - error: 'near "COLLATE": syntax error'
 ...
+-- gh-3052: upper/lower support only default locale
+-- For tr-TR result depends on collation
+box.sql.execute([[CREATE TABLE tu (descriptor CHAR(50) PRIMARY KEY, letter CHAR)]]);
+---
+...
+box.internal.collation.create('TURKISH', 'ICU', 'tr-TR', {strength='primary'});
+---
+...
+box.sql.execute([[INSERT INTO tu VALUES ('Latin Capital Letter I U+0049','I');]])
+---
+...
+box.sql.execute([[INSERT INTO tu VALUES ('Latin Small Letter I U+0069','i');]])
+---
+...
+box.sql.execute([[INSERT INTO tu VALUES ('Latin Capital Letter I With Dot Above U+0130','Ä°');]])
+---
+...
+box.sql.execute([[INSERT INTO tu VALUES ('Latin Small Letter Dotless I U+0131','ı');]])
+---
+...
+-- Without collation
+box.sql.execute([[SELECT descriptor, upper(letter) AS upper,lower(letter) AS lower FROM tu;]])
+---
+- - ['Latin Capital Letter I U+0049', 'I', 'i']
+  - ['Latin Capital Letter I With Dot Above U+0130', 'İ', 'i̇']
+  - ['Latin Small Letter Dotless I U+0131', 'I', 'ı']
+  - ['Latin Small Letter I U+0069', 'I', 'i']
+...
+-- With collation
+box.sql.execute([[SELECT descriptor, upper(letter COLLATE "TURKISH") AS upper,lower(letter COLLATE "TURKISH") AS lower FROM tu;]])
+---
+- - ['Latin Capital Letter I U+0049', 'I', 'ı']
+  - ['Latin Capital Letter I With Dot Above U+0130', 'Ä°', 'i']
+  - ['Latin Small Letter Dotless I U+0131', 'I', 'ı']
+  - ['Latin Small Letter I U+0069', 'Ä°', 'i']
+...
+box.internal.collation.drop('TURKISH')
+---
+...
+-- For de-DE result is actually the same
+box.internal.collation.create('GERMAN', 'ICU', 'de-DE', {strength='primary'});
+---
+...
+box.sql.execute([[INSERT INTO tu VALUES ('German Small Letter Sharp S U+00DF','ß');]])
+---
+...
+-- Without collation
+box.sql.execute([[SELECT descriptor, upper(letter), letter FROM tu where UPPER(letter) = 'SS';]])
+---
+- - ['German Small Letter Sharp S U+00DF', 'SS', 'ß']
+...
+-- With collation
+box.sql.execute([[SELECT descriptor, upper(letter COLLATE "GERMAN"), letter FROM tu where UPPER(letter COLLATE "GERMAN") = 'SS';]])
+---
+- - ['German Small Letter Sharp S U+00DF', 'SS', 'ß']
+...
+box.internal.collation.drop('GERMAN')
+---
+...
+box.sql.execute(([[DROP TABLE tu]]))
+---
+...
 box.schema.user.grant('guest','read,write,execute', 'universe')
 ---
 ...
diff --git a/test/sql/collation.test.lua b/test/sql/collation.test.lua
index ff2c5b22719a11578fd95a12612ff7c2152a12c0..935dea8245bbeb1448edc7cbd964934576f6387a 100644
--- a/test/sql/collation.test.lua
+++ b/test/sql/collation.test.lua
@@ -12,6 +12,29 @@ box.sql.execute("SELECT 1 LIMIT 1 OFFSET 1 COLLATE BINARY;")
 box.sql.execute("SELECT 1 LIMIT 1, 1 COLLATE BINARY;")
 box.sql.execute("SELECT 1 LIMIT 1 COLLATE BINARY, 1;")
 
+-- gh-3052: upper/lower support only default locale
+-- For tr-TR result depends on collation
+box.sql.execute([[CREATE TABLE tu (descriptor CHAR(50) PRIMARY KEY, letter CHAR)]]);
+box.internal.collation.create('TURKISH', 'ICU', 'tr-TR', {strength='primary'});
+box.sql.execute([[INSERT INTO tu VALUES ('Latin Capital Letter I U+0049','I');]])
+box.sql.execute([[INSERT INTO tu VALUES ('Latin Small Letter I U+0069','i');]])
+box.sql.execute([[INSERT INTO tu VALUES ('Latin Capital Letter I With Dot Above U+0130','Ä°');]])
+box.sql.execute([[INSERT INTO tu VALUES ('Latin Small Letter Dotless I U+0131','ı');]])
+-- Without collation
+box.sql.execute([[SELECT descriptor, upper(letter) AS upper,lower(letter) AS lower FROM tu;]])
+-- With collation
+box.sql.execute([[SELECT descriptor, upper(letter COLLATE "TURKISH") AS upper,lower(letter COLLATE "TURKISH") AS lower FROM tu;]])
+box.internal.collation.drop('TURKISH')
+
+-- For de-DE result is actually the same
+box.internal.collation.create('GERMAN', 'ICU', 'de-DE', {strength='primary'});
+box.sql.execute([[INSERT INTO tu VALUES ('German Small Letter Sharp S U+00DF','ß');]])
+-- Without collation
+box.sql.execute([[SELECT descriptor, upper(letter), letter FROM tu where UPPER(letter) = 'SS';]])
+-- With collation
+box.sql.execute([[SELECT descriptor, upper(letter COLLATE "GERMAN"), letter FROM tu where UPPER(letter COLLATE "GERMAN") = 'SS';]])
+box.internal.collation.drop('GERMAN')
+box.sql.execute(([[DROP TABLE tu]]))
 
 box.schema.user.grant('guest','read,write,execute', 'universe')
 cn = remote.connect(box.cfg.listen)