diff --git a/mysql-test/main/skip_grants.result b/mysql-test/main/skip_grants.result
index a8633807571..daf4191a555 100644
--- a/mysql-test/main/skip_grants.result
+++ b/mysql-test/main/skip_grants.result
@@ -139,3 +139,11 @@ drop user baz@baz;
 #
 # End of 10.3 tests
 #
+#
+# MDEV-34501: SIGSEGV in pfs_start_mutex_wait_v1, __strlen_avx2, or __strlen_evex from safe_mutex_lock on CREATE DEFINER when using skip-grant-tables
+#
+CREATE DEFINER=a PROCEDURE p() SELECT 1;
+CREATE DEFINER=a FUNCTION f() RETURNS INT RETURN 100;
+DROP PROCEDURE p;
+DROP FUNCTION f;
+# End of 10.5 tests
diff --git a/mysql-test/main/skip_grants.test b/mysql-test/main/skip_grants.test
index eb8d3c3df88..2c4eddda2b2 100644
--- a/mysql-test/main/skip_grants.test
+++ b/mysql-test/main/skip_grants.test
@@ -164,3 +164,14 @@ drop user baz@baz;
 --echo #
 --echo # End of 10.3 tests
 --echo #
+
+--echo #
+--echo # MDEV-34501: SIGSEGV in pfs_start_mutex_wait_v1, __strlen_avx2, or __strlen_evex from safe_mutex_lock on CREATE DEFINER when using skip-grant-tables
+--echo #
+CREATE DEFINER=a PROCEDURE p() SELECT 1;
+CREATE DEFINER=a FUNCTION f() RETURNS INT RETURN 100;
+
+DROP PROCEDURE p;
+DROP FUNCTION f;
+
+--echo # End of 10.5 tests
diff --git a/mysql-test/main/sp-bugs.result b/mysql-test/main/sp-bugs.result
index bd5883f0a04..c1f64a1fa14 100644
--- a/mysql-test/main/sp-bugs.result
+++ b/mysql-test/main/sp-bugs.result
@@ -388,5 +388,14 @@ ERROR 23000: Column 'c2' in from clause is ambiguous
 DROP PROCEDURE p2;
 DROP TABLE t1, t2;
 #
+# MDEV-34501: SIGSEGV in pfs_start_mutex_wait_v1, __strlen_avx2, or __strlen_evex from safe_mutex_lock on CREATE DEFINER when using skip-grant-tables
+#
+# This test is a duplicate of the one located in the file skip_grants.test
+# and placed here to check the same test case against embedded-server
+CREATE DEFINER=a PROCEDURE p() SELECT 1;
+CREATE DEFINER=a FUNCTION f() RETURNS INT RETURN 100;
+DROP PROCEDURE p;
+DROP FUNCTION f;
+#
 # End of 10.5 tests
 #
diff --git a/mysql-test/main/sp-bugs.test b/mysql-test/main/sp-bugs.test
index f44216fbf46..9a4b867a92b 100644
--- a/mysql-test/main/sp-bugs.test
+++ b/mysql-test/main/sp-bugs.test
@@ -414,6 +414,26 @@ CALL p2 (@a,@c);
 DROP PROCEDURE p2;
 DROP TABLE t1, t2;
 
+--echo #
+--echo # MDEV-34501: SIGSEGV in pfs_start_mutex_wait_v1, __strlen_avx2, or __strlen_evex from safe_mutex_lock on CREATE DEFINER when using skip-grant-tables
+--echo #
+--echo # This test is a duplicate of the one located in the file skip_grants.test
+--echo # and placed here to check the same test case against embedded-server
+
+# Disable warnings before running the following CREATE PROCEDURE/FUNCTION
+# statement since the warning message
+#   "The user specified as a definer ('a'@'%') does not exist"
+# is output in case the test be run against a regular server
+# and isn't output if embedded server is used (@sa sp_process_definer()
+# in sql_parse.cc).
+--disable_warnings
+CREATE DEFINER=a PROCEDURE p() SELECT 1;
+CREATE DEFINER=a FUNCTION f() RETURNS INT RETURN 100;
+--enable_warnings
+
+DROP PROCEDURE p;
+DROP FUNCTION f;
+
 --echo #
 --echo # End of 10.5 tests
 --echo #
diff --git a/sql/sql_acl.cc b/sql/sql_acl.cc
index a7e9ea7d6f7..385d3da18e2 100644
--- a/sql/sql_acl.cc
+++ b/sql/sql_acl.cc
@@ -12944,6 +12944,9 @@ LEX_USER *get_current_user(THD *thd, LEX_USER *user, bool lock)
     if (is_invalid_role_name(user->user.str))
       return 0;
 
+    if (!initialized)
+      return dup;
+
     if (lock)
       mysql_mutex_lock(&acl_cache->lock);
     if (find_acl_role(dup->user.str))
diff --git a/sql/structs.h b/sql/structs.h
index aa50035ac7a..2fbd263c825 100644
--- a/sql/structs.h
+++ b/sql/structs.h
@@ -227,7 +227,7 @@ struct AUTHID
   LEX_CSTRING user, host;
   void init() { memset(this, 0, sizeof(*this)); }
   void copy(MEM_ROOT *root, const LEX_CSTRING *usr, const LEX_CSTRING *host);
-  bool is_role() const { return user.str[0] && !host.str[0]; }
+  bool is_role() const { return user.str[0] && (!host.str || !host.str[0]); }
   void set_lex_string(LEX_CSTRING *l, char *buf)
   {
     if (is_role())