diff --git a/NEWS b/NEWS
index cf28751877fa..a56c03bb9e48 100644
--- a/NEWS
+++ b/NEWS
@@ -54,6 +54,10 @@ PHP                                                                        NEWS
   . Fixed a leak when a persistent connection failed a liveness check
     with no other live PDO handle. (iliaal)
 
+- PDO_ODBC:
+  . Fixed bug GH-23444 (ODBC_ATTR_ASSUME_UTF8 corrupts Unicode data outside
+    Windows). (Calvin Buckley, Lazizbek Ergashev)
+
 - Phar:
   . Fixed bug GH-23418 (Use-after-free when looking up mounted directories).
     (Weilin Du)
diff --git a/ext/pdo_odbc/odbc_stmt.c b/ext/pdo_odbc/odbc_stmt.c
index 8786f2563e52..042c4684a887 100644
--- a/ext/pdo_odbc/odbc_stmt.c
+++ b/ext/pdo_odbc/odbc_stmt.c
@@ -34,6 +34,7 @@ enum pdo_odbc_conv_result {
 
 static int pdo_odbc_sqltype_is_unicode(pdo_odbc_stmt *S, SQLSMALLINT sqltype)
 {
+#ifdef PHP_WIN32
 	if (!S->assume_utf8) return 0;
 	switch (sqltype) {
 #ifdef SQL_WCHAR
@@ -51,6 +52,9 @@ static int pdo_odbc_sqltype_is_unicode(pdo_odbc_stmt *S, SQLSMALLINT sqltype)
 		default:
 			return 0;
 	}
+#else
+	return 0;
+#endif
 }
 
 static int pdo_odbc_utf82ucs2(pdo_stmt_t *stmt, int is_unicode, const char *buf,
@@ -548,7 +552,15 @@ static int odbc_stmt_param_hook(pdo_stmt_t *stmt, struct pdo_bound_param_data *p
 								break;
 						}
 					} else {
-						P->len = SQL_LEN_DATA_AT_EXEC(Z_STRLEN_P(parameter));
+						zend_ulong ulen;
+						if (pdo_odbc_utf82ucs2(stmt, P->is_unicode,
+									Z_STRVAL_P(parameter),
+									Z_STRLEN_P(parameter),
+									&ulen) == PDO_ODBC_CONV_OK) {
+							P->len = SQL_LEN_DATA_AT_EXEC(ulen);
+						} else {
+							P->len = SQL_LEN_DATA_AT_EXEC(Z_STRLEN_P(parameter));
+						}
 					}
 				}
 				return 1;
diff --git a/ext/pdo_odbc/tests/gh23444.phpt b/ext/pdo_odbc/tests/gh23444.phpt
new file mode 100644
index 000000000000..f71fc733839f
--- /dev/null
+++ b/ext/pdo_odbc/tests/gh23444.phpt
@@ -0,0 +1,34 @@
+--TEST--
+GH-23444 (Unicode data is corrupted with ODBC_ATTR_ASSUME_UTF8)
+--EXTENSIONS--
+pdo_odbc
+--SKIPIF--
+<?php
+require 'ext/pdo/tests/pdo_test.inc';
+PDOTest::skip();
+?>
+--FILE--
+<?php
+require 'ext/pdo/tests/pdo_test.inc';
+$db = PDOTest::test_factory(__DIR__ . '/common.phpt');
+$db->exec("CREATE TABLE gh23444 (v NVARCHAR(100))");
+
+// 13 bytes as UTF-8, so an unconverted parameter is an odd number of bytes
+$string = "\u{6e2c}\u{8a66}\u{4e2d}\u{1f418}";
+
+$db->setAttribute(PDO::ODBC_ATTR_ASSUME_UTF8, true);
+$stmt = $db->prepare("INSERT INTO gh23444 VALUES(?)");
+$stmt->execute([$string]);
+
+$stmt = $db->prepare("SELECT v FROM gh23444 WHERE v = ?");
+$stmt->execute([$string]);
+var_dump($stmt->fetchColumn() === $string);
+?>
+--CLEAN--
+<?php
+require 'ext/pdo/tests/pdo_test.inc';
+$db = PDOTest::test_factory(__DIR__ . '/common.phpt');
+$db->exec("DROP TABLE IF EXISTS gh23444");
+?>
+--EXPECT--
+bool(true)