diff --git a/mysql-test/r/user_var.result b/mysql-test/r/user_var.result
index cf82a18ea83..374520ff610 100644
--- a/mysql-test/r/user_var.result
+++ b/mysql-test/r/user_var.result
@@ -450,4 +450,10 @@ DROP TABLE t1;
 select @v:=@v:=sum(1) from dual;
 @v:=@v:=sum(1)
 1
+CREATE TABLE t1(a DECIMAL(31,21));
+INSERT INTO t1 VALUES (0);
+SELECT (@v:=a) <> (@v:=1) FROM t1;
+(@v:=a) <> (@v:=1)
+1
+DROP TABLE t1;
 End of 5.1 tests
diff --git a/mysql-test/t/user_var.test b/mysql-test/t/user_var.test
index 56217fe67d5..efaf8afd91e 100644
--- a/mysql-test/t/user_var.test
+++ b/mysql-test/t/user_var.test
@@ -353,4 +353,16 @@ DROP TABLE t1;
 
 select @v:=@v:=sum(1) from dual;
 
+#
+# Bug #57187: more user variable fun with multiple assignments and
+#             comparison in query
+#
+
+CREATE TABLE t1(a DECIMAL(31,21));
+INSERT INTO t1 VALUES (0);
+
+SELECT (@v:=a) <> (@v:=1) FROM t1;
+
+DROP TABLE t1;
+
 --echo End of 5.1 tests
diff --git a/sql/item_func.cc b/sql/item_func.cc
index 8bb1009ac2c..5a8f65a795a 100644
--- a/sql/item_func.cc
+++ b/sql/item_func.cc
@@ -4064,7 +4064,7 @@ my_decimal *user_var_entry::val_decimal(my_bool *null_value, my_decimal *val)
     int2my_decimal(E_DEC_FATAL_ERROR, *(longlong*) value, 0, val);
     break;
   case DECIMAL_RESULT:
-    val= (my_decimal *)value;
+    my_decimal2decimal((my_decimal *) value, val);
     break;
   case STRING_RESULT:
     str2my_decimal(E_DEC_FATAL_ERROR, value, length, collation.collation, val);