diff --git a/mysql-test/r/dyncol.result b/mysql-test/r/dyncol.result
index aacb5363717..ca6908f449c 100644
--- a/mysql-test/r/dyncol.result
+++ b/mysql-test/r/dyncol.result
@@ -1444,3 +1444,9 @@ column_get(column_create(1, "18446744073709552001" as char), 1 as int)
 Warnings:
 Warning	1918	Encountered illegal value '18446744073709552001' when converting to INT
 Note	1105	Cast to signed converted positive out-of-range integer to it's negative complement
+#
+# MDEV-7505 - Too large scale in DECIMAL dynamic column getter crashes
+#             mysqld
+#
+SELECT COLUMN_GET(`x`, 'y' AS DECIMAL(5,34));
+ERROR 42000: Too big scale 34 specified for ''y''. Maximum is 30.
diff --git a/mysql-test/t/dyncol.test b/mysql-test/t/dyncol.test
index 68e10a5fffe..f0d9467420a 100644
--- a/mysql-test/t/dyncol.test
+++ b/mysql-test/t/dyncol.test
@@ -643,3 +643,9 @@ SELECT
 #
 select column_get(column_create(1, "18446744073709552001" as char), 1 as int);
 
+--echo #
+--echo # MDEV-7505 - Too large scale in DECIMAL dynamic column getter crashes
+--echo #             mysqld
+--echo #
+--error ER_TOO_BIG_SCALE
+SELECT COLUMN_GET(`x`, 'y' AS DECIMAL(5,34));
diff --git a/sql/item_strfunc.cc b/sql/item_strfunc.cc
index eedf1499403..aca66fc29e0 100644
--- a/sql/item_strfunc.cc
+++ b/sql/item_strfunc.cc
@@ -4467,6 +4467,16 @@ null:
 
 void Item_dyncol_get::print(String *str, enum_query_type query_type)
 {
+  /*
+    Parent cast doesn't exist yet, only print dynamic column name. This happens
+    when called from create_func_cast() / wrong_precision_error().
+  */
+  if (!str->length())
+  {
+    args[1]->print(str, query_type);
+    return;
+  }
+
   /* see create_func_dyncol_get */
   DBUG_ASSERT(str->length() >= 5);
   DBUG_ASSERT(strncmp(str->ptr() + str->length() - 5, "cast(", 5) == 0);