diff --git a/timestamp.go b/timestamp.go
index 35ac5143..de059f7e 100644
--- a/timestamp.go
+++ b/timestamp.go
@@ -158,7 +158,7 @@ func (src Timestamp) EncodeText(ci *ConnInfo, buf []byte) ([]byte, error) {
 
 	switch src.InfinityModifier {
 	case None:
-		s = src.Time.Format(pgTimestampFormat)
+		s = src.Time.Truncate(time.Microsecond).Format(pgTimestampFormat)
 	case Infinity:
 		s = "infinity"
 	case NegativeInfinity:
diff --git a/timestamp_test.go b/timestamp_test.go
index eec0a52e..2fdc7171 100644
--- a/timestamp_test.go
+++ b/timestamp_test.go
@@ -32,6 +32,51 @@ func TestTimestampTranscode(t *testing.T) {
 	})
 }
 
+func TestTimestampNanosecondsTruncated(t *testing.T) {
+	tests := []struct {
+		input    time.Time
+		expected time.Time
+	}{
+		{time.Date(2020, 1, 1, 0, 0, 0, 999999999, time.UTC), time.Date(2020, 1, 1, 0, 0, 0, 999999000, time.UTC)},
+		{time.Date(2020, 1, 1, 0, 0, 0, 999999001, time.UTC), time.Date(2020, 1, 1, 0, 0, 0, 999999000, time.UTC)},
+	}
+	for i, tt := range tests {
+		{
+			ts := pgtype.Timestamp{Time: tt.input, Status: pgtype.Present}
+			buf, err := ts.EncodeText(nil, nil)
+			if err != nil {
+				t.Errorf("%d. EncodeText failed - %v", i, err)
+			}
+
+			ts.DecodeText(nil, buf)
+			if err != nil {
+				t.Errorf("%d. DecodeText failed - %v", i, err)
+			}
+
+			if !(ts.Status == pgtype.Present && ts.Time.Equal(tt.expected)) {
+				t.Errorf("%d. EncodeText did not truncate nanoseconds", i)
+			}
+		}
+
+		{
+			ts := pgtype.Timestamp{Time: tt.input, Status: pgtype.Present}
+			buf, err := ts.EncodeBinary(nil, nil)
+			if err != nil {
+				t.Errorf("%d. EncodeBinary failed - %v", i, err)
+			}
+
+			ts.DecodeBinary(nil, buf)
+			if err != nil {
+				t.Errorf("%d. DecodeBinary failed - %v", i, err)
+			}
+
+			if !(ts.Status == pgtype.Present && ts.Time.Equal(tt.expected)) {
+				t.Errorf("%d. EncodeBinary did not truncate nanoseconds", i)
+			}
+		}
+	}
+}
+
 func TestTimestampSet(t *testing.T) {
 	type _time time.Time
 
diff --git a/timestamptz.go b/timestamptz.go
index d390d266..100f44a5 100644
--- a/timestamptz.go
+++ b/timestamptz.go
@@ -160,7 +160,7 @@ func (src Timestamptz) EncodeText(ci *ConnInfo, buf []byte) ([]byte, error) {
 
 	switch src.InfinityModifier {
 	case None:
-		s = src.Time.UTC().Format(pgTimestamptzSecondFormat)
+		s = src.Time.UTC().Truncate(time.Microsecond).Format(pgTimestamptzSecondFormat)
 	case Infinity:
 		s = "infinity"
 	case NegativeInfinity:
diff --git a/timestamptz_test.go b/timestamptz_test.go
index a020b1ec..a088fc08 100644
--- a/timestamptz_test.go
+++ b/timestamptz_test.go
@@ -32,6 +32,51 @@ func TestTimestamptzTranscode(t *testing.T) {
 	})
 }
 
+func TestTimestamptzNanosecondsTruncated(t *testing.T) {
+	tests := []struct {
+		input    time.Time
+		expected time.Time
+	}{
+		{time.Date(2020, 1, 1, 0, 0, 0, 999999999, time.Local), time.Date(2020, 1, 1, 0, 0, 0, 999999000, time.Local)},
+		{time.Date(2020, 1, 1, 0, 0, 0, 999999001, time.Local), time.Date(2020, 1, 1, 0, 0, 0, 999999000, time.Local)},
+	}
+	for i, tt := range tests {
+		{
+			tstz := pgtype.Timestamptz{Time: tt.input, Status: pgtype.Present}
+			buf, err := tstz.EncodeText(nil, nil)
+			if err != nil {
+				t.Errorf("%d. EncodeText failed - %v", i, err)
+			}
+
+			tstz.DecodeText(nil, buf)
+			if err != nil {
+				t.Errorf("%d. DecodeText failed - %v", i, err)
+			}
+
+			if !(tstz.Status == pgtype.Present && tstz.Time.Equal(tt.expected)) {
+				t.Errorf("%d. EncodeText did not truncate nanoseconds", i)
+			}
+		}
+
+		{
+			tstz := pgtype.Timestamptz{Time: tt.input, Status: pgtype.Present}
+			buf, err := tstz.EncodeBinary(nil, nil)
+			if err != nil {
+				t.Errorf("%d. EncodeBinary failed - %v", i, err)
+			}
+
+			tstz.DecodeBinary(nil, buf)
+			if err != nil {
+				t.Errorf("%d. DecodeBinary failed - %v", i, err)
+			}
+
+			if !(tstz.Status == pgtype.Present && tstz.Time.Equal(tt.expected)) {
+				t.Errorf("%d. EncodeBinary did not truncate nanoseconds", i)
+			}
+		}
+	}
+}
+
 func TestTimestamptzSet(t *testing.T) {
 	type _time time.Time