diff --git a/pgtype/numeric.go b/pgtype/numeric.go
index 426b6782..b9827b63 100644
--- a/pgtype/numeric.go
+++ b/pgtype/numeric.go
@@ -109,6 +109,33 @@ func (n Numeric) Float64Value() (Float8, error) {
 	return Float8{Float64: f, Valid: true}, nil
 }
 
+func (n *Numeric) ScanInt64(v Int8) error {
+	if !v.Valid {
+		*n = Numeric{}
+		return nil
+	}
+
+	*n = Numeric{Int: big.NewInt(v.Int64), Valid: true}
+	return nil
+}
+
+func (n Numeric) Int64Value() (Int8, error) {
+	if !n.Valid {
+		return Int8{}, nil
+	}
+
+	bi, err := n.toBigInt()
+	if err != nil {
+		return Int8{}, err
+	}
+
+	if !bi.IsInt64() {
+		return Int8{}, fmt.Errorf("cannot convert %v to int64", n)
+	}
+
+	return Int8{Int64: bi.Int64(), Valid: true}, nil
+}
+
 func (n *Numeric) toBigInt() (*big.Int, error) {
 	if n.Exp == 0 {
 		return n.Int, nil
@@ -450,18 +477,15 @@ func (encodePlanNumericCodecTextFloat64Valuer) Encode(value interface{}, buf []b
 	}
 
 	if math.IsNaN(n.Float64) {
-		return encodeNumericBinary(Numeric{NaN: true, Valid: true}, buf)
+		buf = append(buf, "NaN"...)
 	} else if math.IsInf(n.Float64, 1) {
-		return encodeNumericBinary(Numeric{InfinityModifier: Infinity, Valid: true}, buf)
+		buf = append(buf, "Infinity"...)
 	} else if math.IsInf(n.Float64, -1) {
-		return encodeNumericBinary(Numeric{InfinityModifier: NegativeInfinity, Valid: true}, buf)
+		buf = append(buf, "-Infinity"...)
+	} else {
+		buf = append(buf, strconv.FormatFloat(n.Float64, 'f', -1, 64)...)
 	}
-	num, exp, err := parseNumericString(strconv.FormatFloat(n.Float64, 'f', -1, 64))
-	if err != nil {
-		return nil, err
-	}
-
-	return encodeNumericText(Numeric{Int: num, Exp: exp, Valid: true}, buf)
+	return buf, nil
 }
 
 type encodePlanNumericCodecTextInt64Valuer struct{}
@@ -476,7 +500,8 @@ func (encodePlanNumericCodecTextInt64Valuer) Encode(value interface{}, buf []byt
 		return nil, nil
 	}
 
-	return encodeNumericText(Numeric{Int: big.NewInt(n.Int64), Valid: true}, buf)
+	buf = append(buf, strconv.FormatInt(n.Int64, 10)...)
+	return buf, nil
 }
 
 func encodeNumericText(n Numeric, buf []byte) (newBuf []byte, err error) {
@@ -495,9 +520,20 @@ func encodeNumericText(n Numeric, buf []byte) (newBuf []byte, err error) {
 		return buf, nil
 	}
 
-	buf = append(buf, n.Int.String()...)
-	buf = append(buf, 'e')
-	buf = append(buf, strconv.FormatInt(int64(n.Exp), 10)...)
+	digits := n.Int.String()
+	if n.Exp >= 0 {
+		buf = append(buf, digits...)
+		if n.Exp > 0 {
+			for i := int32(0); i < n.Exp; i++ {
+				buf = append(buf, '0')
+			}
+		}
+	} else {
+		buf = append(buf, digits...)
+		buf = append(buf, 'e')
+		buf = append(buf, strconv.FormatInt(int64(n.Exp), 10)...)
+	}
+
 	return buf, nil
 }
 
diff --git a/pgtype/numeric_test.go b/pgtype/numeric_test.go
index 8be8ce55..3c37ae18 100644
--- a/pgtype/numeric_test.go
+++ b/pgtype/numeric_test.go
@@ -113,6 +113,12 @@ func TestNumericCodec(t *testing.T) {
 		{pgtype.Numeric{}, new(pgtype.Numeric), isExpectedEq(pgtype.Numeric{})},
 		{nil, new(pgtype.Numeric), isExpectedEq(pgtype.Numeric{})},
 	})
+
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "int8", []pgxtest.ValueRoundTripTest{
+		{mustParseNumeric(t, "-1"), new(pgtype.Numeric), isExpectedEqNumeric(mustParseNumeric(t, "-1"))},
+		{mustParseNumeric(t, "0"), new(pgtype.Numeric), isExpectedEqNumeric(mustParseNumeric(t, "0"))},
+		{mustParseNumeric(t, "1"), new(pgtype.Numeric), isExpectedEqNumeric(mustParseNumeric(t, "1"))},
+	})
 }
 
 func TestNumericCodecInfinity(t *testing.T) {