diff --git a/mysql-test/r/loaddata.result b/mysql-test/r/loaddata.result
index 1e488b320d7..0c3f8d04463 100644
--- a/mysql-test/r/loaddata.result
+++ b/mysql-test/r/loaddata.result
@@ -484,4 +484,15 @@ SET character_set_filesystem=default;
 select @@character_set_filesystem;
 @@character_set_filesystem
 binary
+#
+# Bug #51850: crash/memory overlap when using load data infile and set 
+#  col equal to itself!
+#
+CREATE TABLE t1(col0 LONGBLOB);
+SELECT 'test' INTO OUTFILE 't1.txt';
+LOAD DATA INFILE 't1.txt' IGNORE INTO TABLE t1 SET col0=col0;
+SELECT * FROM t1;
+col0
+test
+DROP TABLE t1;
 End of 5.1 tests
diff --git a/mysql-test/t/loaddata.test b/mysql-test/t/loaddata.test
index 7bfe2491c7c..a32fee6b46e 100644
--- a/mysql-test/t/loaddata.test
+++ b/mysql-test/t/loaddata.test
@@ -532,5 +532,19 @@ SET character_set_filesystem=default;
 select @@character_set_filesystem;
 
 
+--echo #
+--echo # Bug #51850: crash/memory overlap when using load data infile and set 
+--echo #  col equal to itself!
+--echo #
+
+CREATE TABLE t1(col0 LONGBLOB);
+SELECT 'test' INTO OUTFILE 't1.txt';
+LOAD DATA INFILE 't1.txt' IGNORE INTO TABLE t1 SET col0=col0;
+SELECT * FROM t1;
+
+DROP TABLE t1;
+let $MYSQLD_DATADIR= `select @@datadir`;
+remove_file $MYSQLD_DATADIR/test/t1.txt;
+
 
 --echo End of 5.1 tests
diff --git a/sql/item.cc b/sql/item.cc
index d253e19e068..809377e80b3 100644
--- a/sql/item.cc
+++ b/sql/item.cc
@@ -5063,14 +5063,22 @@ int Item_field::save_in_field(Field *to, bool no_conversions)
   if (result_field->is_null())
   {
     null_value=1;
-    res= set_field_to_null_with_conversions(to, no_conversions);
+    return set_field_to_null_with_conversions(to, no_conversions);
   }
-  else
+  to->set_notnull();
+
+  /*
+    If we're setting the same field as the one we're reading from there's 
+    nothing to do. This can happen in 'SET x = x' type of scenarios.
+  */  
+  if (to == result_field)
   {
-    to->set_notnull();
-    res= field_conv(to,result_field);
     null_value=0;
+    return 0;
   }
+
+  res= field_conv(to,result_field);
+  null_value=0;
   return res;
 }