diff --git a/src/math/all_test.go b/src/math/all_test.go
index c2d2efcd97..ed42941780 100644
--- a/src/math/all_test.go
+++ b/src/math/all_test.go
@@ -1528,6 +1528,7 @@ var vflog1pSC = []float64{
 	0,
 	Inf(1),
 	NaN(),
+	4503599627370496.5, // Issue #29488
 }
 var log1pSC = []float64{
 	NaN(),
@@ -1537,6 +1538,7 @@ var log1pSC = []float64{
 	0,
 	Inf(1),
 	NaN(),
+	36.04365338911715, // Issue #29488
 }
 
 var vfmodfSC = []float64{
diff --git a/src/math/log1p.go b/src/math/log1p.go
index b128a1620c..c4ec61b225 100644
--- a/src/math/log1p.go
+++ b/src/math/log1p.go
@@ -151,12 +151,13 @@ func log1p(x float64) float64 {
 			u = 1.0 + x
 			iu = Float64bits(u)
 			k = int((iu >> 52) - 1023)
+			// correction term
 			if k > 0 {
 				c = 1.0 - (u - x)
 			} else {
-				c = x - (u - 1.0) // correction term
-				c /= u
+				c = x - (u - 1.0)
 			}
+			c /= u
 		} else {
 			u = x
 			iu = Float64bits(u)