diff --git a/pgtype/numeric.go b/pgtype/numeric.go
index bf42d5569..e33597039 100644
--- a/pgtype/numeric.go
+++ b/pgtype/numeric.go
@@ -234,7 +234,12 @@ func (n Numeric) MarshalJSON() ([]byte, error) {
 		return []byte("null"), nil
 	}
 
-	if n.NaN {
+	switch {
+	case n.InfinityModifier == Infinity:
+		return []byte(`"infinity"`), nil
+	case n.InfinityModifier == NegativeInfinity:
+		return []byte(`"-infinity"`), nil
+	case n.NaN:
 		return []byte(`"NaN"`), nil
 	}
 
diff --git a/pgtype/range_test.go b/pgtype/range_test.go
index 2a0534134..99fe03e7c 100644
--- a/pgtype/range_test.go
+++ b/pgtype/range_test.go
@@ -318,14 +318,14 @@ func TestRangeNumericMarshalJSON(t *testing.T) {
 			LowerType: Exclusive,
 			UpperType: Exclusive,
 			Valid:     true,
-		}, result: `"(NaN,16)"`},
+		}, result: `"(-infinity,16)"`},
 		{src: Range[Numeric]{
 			Lower:     Numeric{Int: big.NewInt(-16), Valid: true},
 			Upper:     Numeric{InfinityModifier: Infinity, NaN: true, Valid: true},
 			LowerType: Inclusive,
 			UpperType: Exclusive,
 			Valid:     true,
-		}, result: `"[-16,NaN)"`},
+		}, result: `"[-16,infinity)"`},
 	}
 
 	for i, tt := range tests {