diff --git a/mysql-test/r/func_misc.result b/mysql-test/r/func_misc.result
index e21e7903459..a95308b0e66 100644
--- a/mysql-test/r/func_misc.result
+++ b/mysql-test/r/func_misc.result
@@ -345,4 +345,19 @@ SELECT COALESCE(a) = COALESCE(b) FROM t1;
 COALESCE(a) = COALESCE(b)
 1
 DROP TABLE t1;
-End of tests
+#
+# Bug #54461: crash with longblob and union or update with subquery
+#
+CREATE TABLE t1 (a INT, b LONGBLOB);
+INSERT INTO t1 VALUES (1, '2'), (2, '3'), (3, '2');
+SELECT DISTINCT LEAST(a, (SELECT b FROM t1 LIMIT 1)) FROM t1 UNION SELECT 1;
+LEAST(a, (SELECT b FROM t1 LIMIT 1))
+1
+2
+SELECT DISTINCT GREATEST(a, (SELECT b FROM t1 LIMIT 1)) FROM t1 UNION SELECT 1;
+GREATEST(a, (SELECT b FROM t1 LIMIT 1))
+2
+3
+1
+DROP TABLE t1;
+End of 5.1 tests
diff --git a/mysql-test/t/func_misc.test b/mysql-test/t/func_misc.test
index a60eb9cf845..5d93813a9ff 100644
--- a/mysql-test/t/func_misc.test
+++ b/mysql-test/t/func_misc.test
@@ -478,4 +478,17 @@ SELECT COALESCE(a) = COALESCE(b) FROM t1;
 
 DROP TABLE t1;
 
---echo End of tests
+
+--echo #
+--echo # Bug #54461: crash with longblob and union or update with subquery
+--echo #
+
+CREATE TABLE t1 (a INT, b LONGBLOB);
+INSERT INTO t1 VALUES (1, '2'), (2, '3'), (3, '2');
+
+SELECT DISTINCT LEAST(a, (SELECT b FROM t1 LIMIT 1)) FROM t1 UNION SELECT 1;
+SELECT DISTINCT GREATEST(a, (SELECT b FROM t1 LIMIT 1)) FROM t1 UNION SELECT 1;
+
+DROP TABLE t1;
+
+--echo End of 5.1 tests
diff --git a/mysys/stacktrace.c b/mysys/stacktrace.c
index 675910d2b20..ba62062ebc0 100644
--- a/mysys/stacktrace.c
+++ b/mysys/stacktrace.c
@@ -83,7 +83,9 @@ void my_print_stacktrace(uchar* stack_bottom __attribute__((unused)),
 
 #if BACKTRACE_DEMANGLE
 
-char __attribute__ ((weak)) *my_demangle(const char *mangled_name, int *status)
+char __attribute__ ((weak)) *
+my_demangle(const char *mangled_name __attribute__((unused)),
+            int *status __attribute__((unused)))
 {
   return NULL;
 }
diff --git a/sql/item_func.cc b/sql/item_func.cc
index 833eac6893b..7812460bd2b 100644
--- a/sql/item_func.cc
+++ b/sql/item_func.cc
@@ -2531,6 +2531,8 @@ void Item_func_min_max::fix_length_and_dec()
                                                                  decimals,
                                                                  unsigned_flag));
   }
+  else if (cmp_type == REAL_RESULT)
+    max_length= float_length(decimals);
   cached_field_type= agg_field_type(args, arg_count);
 }
 
diff --git a/sql/sql_lex.cc b/sql/sql_lex.cc
index 59a1085728a..79d91a461db 100644
--- a/sql/sql_lex.cc
+++ b/sql/sql_lex.cc
@@ -1436,8 +1436,6 @@ int lex_one_token(void *arg, void *yythd)
           }
           else
           {
-            const char* version_mark= lip->get_ptr() - 1;
-            DBUG_ASSERT(*version_mark == '!');
             /*
               Patch and skip the conditional comment to avoid it
               being propagated infinitely (eg. to a slave).
@@ -1446,7 +1444,6 @@ int lex_one_token(void *arg, void *yythd)
             comment_closed= ! consume_comment(lip, 1);
             if (! comment_closed)
             {
-              DBUG_ASSERT(pcom == version_mark);
               *pcom= '!';
             }
             /* version allowed to have one level of comment inside. */