diff --git a/Project.toml b/Project.toml
index 7abff29..6d485ee 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "UnixTimes"
 uuid = "ab1a18e7-b408-4913-896c-624bb82ed7f4"
 authors = ["Christian Rorvik <christian.rorvik@gmail.com>"]
-version = "1.7.2"
+version = "1.8.0"
 
 [deps]
 Dates = "ade2ca70-3891-5945-98fb-dc099432e06a"
diff --git a/src/UnixTimes.jl b/src/UnixTimes.jl
index 9bfa05a..a417fb0 100644
--- a/src/UnixTimes.jl
+++ b/src/UnixTimes.jl
@@ -63,14 +63,34 @@ UnixTime(x::Date, y::Time) =
 const DATEFORMAT = dateformat"yyyy-mm-ddTHH:MM:SS.sss"
 
 function UnixTime(s::AbstractString)
-    try
-        @assert length(s) == 29
-        dt = DateTime(chop(s; tail=6), DATEFORMAT)
-        ns = Nanosecond(parse(Int, last(s, 6)))
-        UnixTime(dt) + ns
-    catch
-        throw(ArgumentError("Invalid UnixTime string"))
+    # Find the decimal point if it exists
+    dot_idx = findfirst('.', s)
+
+    # No fractional seconds, parse as DateTime
+    isnothing(dot_idx) && return UnixTime(DateTime(s, DATEFORMAT))
+
+    # Split into datetime and fractional parts
+    dt_part = @view s[1:(dot_idx - 1)]
+    frac_part = @view s[(dot_idx + 1):end]
+
+    # Parse the datetime part
+    dt = DateTime(dt_part, DATEFORMAT)
+
+    # Parse fractional seconds (can be 1-9 digits)
+    if isempty(frac_part) || !all(isdigit, frac_part)
+        throw(ArgumentError("Invalid fractional seconds in UnixTime string"))
     end
+
+    # Convert fractional seconds to nanoseconds
+    # Pad or truncate to 9 digits (nanosecond precision)
+    frac_digits = length(frac_part)
+    ns_value = if frac_digits <= 9
+        parse(Int, frac_part) * 10^(9 - frac_digits)
+    else
+        parse(Int, frac_part[1:9])
+    end
+
+    return UnixTime(dt) + Nanosecond(ns_value)
 end
 
 function Base.convert(::Type{UnixTime}, x::DateTime)
@@ -78,6 +98,9 @@ function Base.convert(::Type{UnixTime}, x::DateTime)
     UnixTime(Dates.UTInstant(Nanosecond(instant_ns)))
 end
 
+# Promotion rules for comparing UnixTime with DateTime
+Base.promote_rule(::Type{UnixTime}, ::Type{DateTime}) = UnixTime
+
 function Base.show(io::IO, x::UnixTime)
     xdt = convert(DateTime, x)
     print(io, Dates.format(xdt, DATEFORMAT))
diff --git a/test/runtests.jl b/test/runtests.jl
index ef499a8..94fbfa4 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -48,9 +48,22 @@ end
     x = UnixTime(2020, 1, 2, 3, 4, 5, 6, 7, 8)
     @test string(x) == "2020-01-02T03:04:05.006007008"
     @test UnixTime(string(x)) == x
-    @test_throws ArgumentError UnixTime("2025-01-28T15:49:36.5901397023")
-    @test_throws ArgumentError UnixTime("2025-01-28T15:49:36.59013970")
-    @test_throws ArgumentError UnixTime(repeat("a", 29))
+
+    # Test various string formats
+    @test UnixTime("2020-01-02T03:04:05") == UnixTime(2020, 1, 2, 3, 4, 5)
+    @test UnixTime("2020-01-02T03:04:05.1") == UnixTime(2020, 1, 2, 3, 4, 5, 100)
+    @test UnixTime("2020-01-02T03:04:05.12") == UnixTime(2020, 1, 2, 3, 4, 5, 120)
+    @test UnixTime("2020-01-02T03:04:05.123") == UnixTime(2020, 1, 2, 3, 4, 5, 123)
+    @test UnixTime("2020-01-02T03:04:05.1234") == UnixTime(2020, 1, 2, 3, 4, 5, 123, 400)
+    @test UnixTime("2020-01-02T03:04:05.123456") == UnixTime(2020, 1, 2, 3, 4, 5, 123, 456)
+    @test UnixTime("2020-01-02T03:04:05.123456789") == UnixTime(2020, 1, 2, 3, 4, 5, 123, 456, 789)
+
+    # Test truncation of extra digits
+    @test UnixTime("2020-01-02T03:04:05.1234567890") == UnixTime(2020, 1, 2, 3, 4, 5, 123, 456, 789)
+
+    # Test invalid formats
+    @test_throws ArgumentError UnixTime("2020-01-02T03:04:05.")
+    @test_throws ArgumentError UnixTime("2020-01-02T03:04:05.abc")
 end
 
 @testset "arithmetic" begin
@@ -102,4 +115,15 @@ end
     @test collect(t1:p:t2) isa Vector
 end
 
+@testset "comparison with DateTime" begin
+    ut = UnixTime(2001, 03, 21, 13, 10, 0, 0)
+    dt = DateTime("2001-03-21T13:10:00")
+
+    @test ut == dt
+    @test ut > DateTime("2001-03-21T13:00:00")
+    @test ut < DateTime("2001-03-21T13:20:00")
+    @test DateTime("2001-03-21T13:20:00") > ut
+    @test UnixTime(2001, 03, 21, 13, 10, 0, 114, 549, 673) > dt
+end
+
 end