diff --git a/src/IO/ReadHelpers.h b/src/IO/ReadHelpers.h
index feacbd085c2..664c4daf8e2 100644
--- a/src/IO/ReadHelpers.h
+++ b/src/IO/ReadHelpers.h
@@ -908,6 +908,8 @@ inline ReturnType readDateTimeTextImpl(DateTime64 & datetime64, UInt32 scale, Re
         return ReturnType(false);
     }
 
+    int negative_multiplier = 1;
+
     DB::DecimalUtils::DecimalComponents<DateTime64> components{static_cast<DateTime64::NativeType>(whole), 0};
 
     if (!buf.eof() && *buf.position() == '.')
@@ -934,29 +936,17 @@ inline ReturnType readDateTimeTextImpl(DateTime64 & datetime64, UInt32 scale, Re
         while (!buf.eof() && isNumericASCII(*buf.position()))
             ++buf.position();
 
-        /// Keep sign of fractional part the same with whole part if datetime64 is negative
-        /// Case1:
-        ///     1965-12-12 12:12:12.123
-        ///     => whole = -127914468, fractional = 123(coefficient>0)
-        ///     => new whole = -127914467, new fractional = 877(coefficient<0)
-        ///
-        /// Case2:
-        ///     1969-12-31 23:59:59.123
-        ///     => whole = -1, fractional = 123(coefficient>0)
-        ///     => new whole = 0, new fractional = -877(coefficient>0)
+        /// Fractional part (subseconds) is treated as positive by users
+        /// (as DateTime64 itself is a positive, although underlying decimal is negative),
+        /// so it needs proper handling
         if (components.whole < 0 && components.fractional != 0)
         {
             const auto scale_multiplier = DecimalUtils::scaleMultiplier<DateTime64::NativeType>(scale);
             ++components.whole;
-            if (components.whole)
+            components.fractional = scale_multiplier - components.fractional;
+            if (!components.whole)
             {
-                /// whole keep the sign, fractional should be non-negative
-                components.fractional = scale_multiplier - components.fractional;
-            }
-            else
-            {
-                /// when whole is zero, fractional should keep the sign
-                components.fractional = components.fractional - scale_multiplier;
+                negative_multiplier = -1;
             }
         }
     }
@@ -969,7 +959,7 @@ inline ReturnType readDateTimeTextImpl(DateTime64 & datetime64, UInt32 scale, Re
         components.whole = components.whole / common::exp10_i32(scale);
     }
 
-    datetime64 = DecimalUtils::decimalFromComponents<DateTime64>(components, scale);
+    datetime64 = negative_multiplier * DecimalUtils::decimalFromComponents<DateTime64>(components, scale);
 
     return ReturnType(true);
 }