diff --git a/src/strconv/atof.go b/src/strconv/atof.go
index 504b9613fb..0903fa155a 100644
--- a/src/strconv/atof.go
+++ b/src/strconv/atof.go
@@ -654,6 +654,9 @@ func atof64(s string) (f float64, err error) {
 // If s is syntactically well-formed but is more than 1/2 ULP
 // away from the largest floating point number of the given size,
 // ParseFloat returns f = ±Inf, err.Err = ErrRange.
+//
+// ParseFloat recognizes the strings "NaN", "+Inf", and "-Inf" as their
+// respective special floating point values. It ignores case when matching.
 func ParseFloat(s string, bitSize int) (float64, error) {
 	if !underscoreOK(s) {
 		return 0, syntaxError(fnParseFloat, s)
diff --git a/src/strconv/example_test.go b/src/strconv/example_test.go
index 46cfd432fb..50f6b20fee 100644
--- a/src/strconv/example_test.go
+++ b/src/strconv/example_test.go
@@ -232,7 +232,7 @@ func ExampleParseFloat() {
 	if s, err := strconv.ParseFloat("inf", 32); err == nil {
 		fmt.Printf("%T, %v\n", s, s)
 	}
-	if s, err := strconv.ParseFloat("Inf", 32); err == nil {
+	if s, err := strconv.ParseFloat("+Inf", 32); err == nil {
 		fmt.Printf("%T, %v\n", s, s)
 	}
 	if s, err := strconv.ParseFloat("-Inf", 32); err == nil {