diff --git a/src/schema/yaml-1.1/timestamp.ts b/src/schema/yaml-1.1/timestamp.ts
index 2093f3ae..958bf1d7 100644
--- a/src/schema/yaml-1.1/timestamp.ts
+++ b/src/schema/yaml-1.1/timestamp.ts
@@ -83,12 +83,18 @@ export const timestamp: ScalarTag & { test: RegExp } = {
   // may be omitted altogether, resulting in a date format. In such a case, the time part is
   // assumed to be 00:00:00Z (start of day, UTC).
   test: RegExp(
-    '^([0-9]{4})-([0-9]{1,2})-([0-9]{1,2})' + // YYYY-Mm-Dd
+    '^([0-9]{4})-?([0-9]{1,2})-?([0-9]{1,2})' + // YYYY-?Mm-?Dd
       '(?:' + // time is optional
       '(?:t|T|[ \\t]+)' + // t | T | whitespace
-      '([0-9]{1,2}):([0-9]{1,2}):([0-9]{1,2}(\\.[0-9]+)?)' + // Hh:Mm:Ss(.ss)?
-      '(?:[ \\t]*(Z|[-+][012]?[0-9](?::[0-9]{2})?))?' + // Z | +5 | -03:30
-      ')?$'
+      '([0-9]{1,2})' + // Hh
+      '(?:' + // minutes are optional
+      ':?([0-9]{1,2})' + // :?Mm
+      '(?:' + // seconds are optionals
+      ':?([0-9]{1,2}(\\.[0-9]{1,3})?)' + // :?Ss(.sss)?
+      '(?:[ \\t]*(Z|[-+][012]?[0-9](?::?[0-9]{2})?))?' + // Z | +5 | -03:30
+      ')?' + // end seconds
+      ')?' + // end minutes
+      ')?$' // end time
   ),
 
   resolve(str) {
@@ -116,5 +122,5 @@ export const timestamp: ScalarTag & { test: RegExp } = {
   },
 
   stringify: ({ value }) =>
-    (value as Date).toISOString().replace(/((T00:00)?:00)?\.000Z$/, '')
+    (value as Date).toISOString().replace(/(((T00)?:00)?:00)?\.000Z$/, '')
 }
diff --git a/tests/doc/types.ts b/tests/doc/types.ts
index 31658aa3..db134ca7 100644
--- a/tests/doc/types.ts
+++ b/tests/doc/types.ts
@@ -660,6 +660,9 @@ english: null
 ---
 canonical:        2001-12-15T02:59:43.1Z
 valid iso8601:    2001-12-14t21:59:43.10-05:00
+no secs:          2001-12-14T01:02
+no mins:          2001-12-14T01
+simplified iso:   20011214T215943.10-5
 space separated:  2001-12-14 21:59:43.10 -5
 no time zone (Z): 2001-12-15 2:59:43.10
 date (00:00:00Z): 2002-12-14`
@@ -671,6 +674,9 @@ date (00:00:00Z): 2002-12-14`
       expect(doc.toJSON()).toMatchObject({
         canonical: '2001-12-15T02:59:43.100Z',
         'valid iso8601': '2001-12-15T02:59:43.100Z',
+        'no secs': '2001-12-14T01:02:00.000Z',
+        'no mins': '2001-12-14T01:00:00.000Z',
+        'simplified iso': '2001-12-15T02:59:43.100Z',
         'space separated': '2001-12-15T02:59:43.100Z',
         'no time zone (Z)': '2001-12-15T02:59:43.100Z',
         'date (00:00:00Z)': '2002-12-14T00:00:00.000Z'
@@ -679,6 +685,9 @@ date (00:00:00Z): 2002-12-14`
 ---
 canonical: 2001-12-15T02:59:43.100Z
 valid iso8601: 2001-12-15T02:59:43.100Z
+no secs: 2001-12-14T01:02
+no mins: 2001-12-14T01
+simplified iso: 2001-12-15T02:59:43.100Z
 space separated: 2001-12-15T02:59:43.100Z
 no time zone (Z): 2001-12-15T02:59:43.100Z
 date (00:00:00Z): 2002-12-14\n`)