diff --git a/README.md b/README.md
index 4af99cc..b420b10 100644
--- a/README.md
+++ b/README.md
@@ -126,7 +126,7 @@ It is possible to access directly the sqlite database using
 ## Specifying times
 
 Some arguments accept a time as value, like `t in`'s `--at` or `t d --start`.
-This are the accepted formats:
+These are the accepted formats:
 
 **Something similar to ISO format** will be parsed as a time in the computer's
 timezone.
diff --git a/src/error.rs b/src/error.rs
index e381da1..291d1ca 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -27,7 +27,33 @@ pub enum Error {
     #[error("Couldn't parse yaml file at: {path}\nwith error: {error}")]
     YamlError{ path: PathBuf, error: serde_yaml::Error},
 
-    #[error("Could not understand '{0}' as a date format.")]
+    #[error("Could not understand '{0}' as a date format. Some options are:
+
+Something similar to ISO format will be parsed as a time in the computer's
+timezone.
+
+* '2021-01-13' a date
+* '2019-05-03 11:13' a date with portions of a time
+
+ISO format with offset or UTC will be parsed as a time in the specified
+timezone. Use 'Z' for 'UTC' and an offset for everything else
+
+* '2021-01-13Z'
+* '2005-10-14 19:20:35+05:00'
+
+something that looks like an hour will be parsed as a time in the current
+day in the computer's timezone. Add 'Z' or an offset to specify the timezone.
+
+* '11:30'
+* '23:50:45' (with seconds)
+
+some human times, for now restricted to time ago:
+
+* 'an hour ago'
+* 'a minute ago'
+* '50 min ago'
+* '1h30m ago'
+* 'two hours thirty minutes ago'")]
     DateTimeParseError(String),
 
     #[error("IOError: {0}")]