diff --git a/src/Functions/IFunction.cpp b/src/Functions/IFunction.cpp
index 0a8e8f426b0..43b344bebc4 100644
--- a/src/Functions/IFunction.cpp
+++ b/src/Functions/IFunction.cpp
@@ -149,8 +149,7 @@ ColumnPtr wrapInNullable(const ColumnPtr & src, const ColumnsWithTypeAndName & a
                 const NullMap & src_null_map = assert_cast<const ColumnUInt8 &>(*null_map_column).getData();
 
                 for (size_t i = 0, size = result_null_map.size(); i < size; ++i)
-                    if (src_null_map[i])
-                        result_null_map[i] = 1;
+                    result_null_map[i] |= src_null_map[i];
 
                 result_null_map_column = std::move(mutable_result_null_map_column);
             }
@@ -179,10 +178,8 @@ NullPresence getNullPresense(const ColumnsWithTypeAndName & args)
 
     for (const auto & elem : args)
     {
-        if (!res.has_nullable)
-            res.has_nullable = elem.type->isNullable();
-        if (!res.has_null_constant)
-            res.has_null_constant = elem.type->onlyNull();
+        res.has_nullable |= elem.type->isNullable();
+        res.has_null_constant |= elem.type->onlyNull();
     }
 
     return res;