diff --git a/src/cbor/from_cbor.cr b/src/cbor/from_cbor.cr
index 4979fa8..08f1be3 100644
--- a/src/cbor/from_cbor.cr
+++ b/src/cbor/from_cbor.cr
@@ -133,9 +133,9 @@ end
 # specified by [Section 2.4.1 of RFC 7049][1].
 #
 # [1]: https://tools.ietf.org/html/rfc7049#section-2.4.1
-def Time.new(decoder : CBOR::Decoder)
+def Time.new(decoder : CBOR::Decoder) : Time
   # In case Time is formatted as a JSON#to_json String.
-  case decoder.current_token
+  value = case decoder.current_token
   when CBOR::Token::StringT
     Time::Format::RFC_3339.parse(decoder.read_string)
   else
@@ -153,6 +153,12 @@ def Time.new(decoder : CBOR::Decoder)
       raise CBOR::ParseError.new("Expected tag to have value 0 or 1, got #{tag.value}")
     end
   end
+
+  unless value
+    raise CBOR::ParseError.new("could not parse time representation")
+  end
+
+  value
 end
 
 # Reads the CBOR value as a BigInt.