diff --git a/src/Functions/UTCTimestamp.cpp b/src/Functions/UTCTimestamp.cpp
index 9b114754061..218c7fa5c1c 100644
--- a/src/Functions/UTCTimestamp.cpp
+++ b/src/Functions/UTCTimestamp.cpp
@@ -79,7 +79,7 @@ public:
 
     bool isDeterministic() const override { return false; }
 
-    bool isVariadic() const override { return true; }
+    bool isVariadic() const override { return false; }
 
     size_t getNumberOfArguments() const override { return 0; }
     static FunctionOverloadResolverPtr create(ContextPtr) { return std::make_unique<UTCTimestampOverloadResolver>(); }
diff --git a/src/Functions/timeDiff.cpp b/src/Functions/timeDiff.cpp
index 9081351998f..0353dbf7c51 100644
--- a/src/Functions/timeDiff.cpp
+++ b/src/Functions/timeDiff.cpp
@@ -47,9 +47,9 @@ public:
         return name;
     }
 
-    bool isVariadic() const override { return true; }
+    bool isVariadic() const override { return false; }
     bool isSuitableForShortCircuitArgumentsExecution(const DataTypesWithConstInfo & /*arguments*/) const override { return true; }
-    size_t getNumberOfArguments() const override { return 0; }
+    size_t getNumberOfArguments() const override { return 2; }
 
     DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override
     {