diff --git a/doc/go1.20.html b/doc/go1.20.html
index 324d59ed6e..1fef45204e 100644
--- a/doc/go1.20.html
+++ b/doc/go1.20.html
@@ -1200,9 +1200,8 @@ proxyHandler := &httputil.ReverseProxy{
     </p>
 
     <p><!-- CL 444277 -->
-      The <a href="/pkg/time/#Time.MarshalJSON"><code>Time.MarshalJSON</code></a> and
-      <a href="/pkg/time/#Time.UnmarshalJSON"><code>Time.UnmarshalJSON</code></a> methods
-      are now more strict about adherence to RFC 3339.
+      The <a href="/pkg/time/#Time.MarshalJSON"><code>Time.MarshalJSON</code></a> method
+      is now more strict about adherence to RFC 3339.
     </p>
   </dd>
 </dl><!-- time -->
diff --git a/src/time/format_rfc3339.go b/src/time/format_rfc3339.go
index a9c295df97..1151666c3e 100644
--- a/src/time/format_rfc3339.go
+++ b/src/time/format_rfc3339.go
@@ -155,7 +155,8 @@ func parseRFC3339[bytes []byte | string](s bytes, local *Location) (Time, bool)
 func parseStrictRFC3339(b []byte) (Time, error) {
 	t, ok := parseRFC3339(b, Local)
 	if !ok {
-		if _, err := Parse(RFC3339, string(b)); err != nil {
+		t, err := Parse(RFC3339, string(b))
+		if err != nil {
 			return Time{}, err
 		}
 
@@ -164,6 +165,10 @@ func parseStrictRFC3339(b []byte) (Time, error) {
 		// See https://go.dev/issue/54580.
 		num2 := func(b []byte) byte { return 10*(b[0]-'0') + (b[1] - '0') }
 		switch {
+		// TODO(https://go.dev/issue/54580): Strict parsing is disabled for now.
+		// Enable this again with a GODEBUG opt-out.
+		case true:
+			return t, nil
 		case b[len("2006-01-02T")+1] == ':': // hour must be two digits
 			return Time{}, &ParseError{RFC3339, string(b), "15", string(b[len("2006-01-02T"):][:1]), ""}
 		case b[len("2006-01-02T15:04:05")] == ',': // sub-second separator must be a period
diff --git a/src/time/time_test.go b/src/time/time_test.go
index ddf77cccb4..4221efec88 100644
--- a/src/time/time_test.go
+++ b/src/time/time_test.go
@@ -830,10 +830,10 @@ func TestUnmarshalInvalidTimes(t *testing.T) {
 	}{
 		{`{}`, "Time.UnmarshalJSON: input is not a JSON string"},
 		{`[]`, "Time.UnmarshalJSON: input is not a JSON string"},
-		{`"2000-01-01T1:12:34Z"`, `parsing time "2000-01-01T1:12:34Z" as "2006-01-02T15:04:05Z07:00": cannot parse "1" as "15"`},
-		{`"2000-01-01T00:00:00,000Z"`, `parsing time "2000-01-01T00:00:00,000Z" as "2006-01-02T15:04:05Z07:00": cannot parse "," as "."`},
-		{`"2000-01-01T00:00:00+24:00"`, `parsing time "2000-01-01T00:00:00+24:00": timezone hour out of range`},
-		{`"2000-01-01T00:00:00+00:60"`, `parsing time "2000-01-01T00:00:00+00:60": timezone minute out of range`},
+		{`"2000-01-01T1:12:34Z"`, `<nil>`},
+		{`"2000-01-01T00:00:00,000Z"`, `<nil>`},
+		{`"2000-01-01T00:00:00+24:00"`, `<nil>`},
+		{`"2000-01-01T00:00:00+00:60"`, `<nil>`},
 		{`"2000-01-01T00:00:00+123:45"`, `parsing time "2000-01-01T00:00:00+123:45" as "2006-01-02T15:04:05Z07:00": cannot parse "+123:45" as "Z07:00"`},
 	}
 
@@ -842,13 +842,13 @@ func TestUnmarshalInvalidTimes(t *testing.T) {
 
 		want := tt.want
 		err := json.Unmarshal([]byte(tt.in), &ts)
-		if err == nil || err.Error() != want {
+		if fmt.Sprint(err) != want {
 			t.Errorf("Time.UnmarshalJSON(%s) = %v, want %v", tt.in, err, want)
 		}
 
 		if strings.HasPrefix(tt.in, `"`) && strings.HasSuffix(tt.in, `"`) {
 			err = ts.UnmarshalText([]byte(strings.Trim(tt.in, `"`)))
-			if err == nil || err.Error() != want {
+			if fmt.Sprint(err) != want {
 				t.Errorf("Time.UnmarshalText(%s) = %v, want %v", tt.in, err, want)
 			}
 		}