diff --git a/src/math/big/float.go b/src/math/big/float.go
index 29dbc0d..adb914d 100644
--- a/src/math/big/float.go
+++ b/src/math/big/float.go
@@ -292,7 +292,7 @@
 	if m == 0 {
 		// 0.0 or Inf
 		if x.exp != 0 && x.exp != infExp {
-			panic(fmt.Sprintf("%empty matissa with invalid exponent %d", x.exp))
+			panic(fmt.Sprintf("empty matissa with invalid exponent %d", x.exp))
 		}
 		return
 	}
@@ -842,7 +842,7 @@
 	return z, acc
 }
 
-// Rat returns the result of converting x into a quotient;
+// Rat returns the rational number corresponding to x;
 // or nil if x is an infinity.
 // If a non-nil *Rat argument z is provided, Rat stores
 // the result in z instead of allocating a new Rat.
diff --git a/src/math/big/int_test.go b/src/math/big/int_test.go
index cb8c76b..dff8057 100644
--- a/src/math/big/int_test.go
+++ b/src/math/big/int_test.go
@@ -290,15 +290,6 @@
 	}
 }
 
-var bitsTests = []nat{
-	nil,
-	{0},
-	{1},
-	{0, 1, 2, 3, 4},
-	{4, 3, 2, 1, 0},
-	{4, 3, 2, 1, 0, 0, 0, 0},
-}
-
 func norm(x nat) nat {
 	i := len(x)
 	for i > 0 && x[i-1] == 0 {
@@ -308,7 +299,14 @@
 }
 
 func TestBits(t *testing.T) {
-	for _, test := range bitsTests {
+	for _, test := range []nat{
+		nil,
+		{0},
+		{1},
+		{0, 1, 2, 3, 4},
+		{4, 3, 2, 1, 0},
+		{4, 3, 2, 1, 0, 0, 0, 0},
+	} {
 		var z Int
 		z.neg = true
 		got := z.SetBits(test)
@@ -318,7 +316,7 @@
 		}
 
 		if got.neg {
-			t.Errorf("SetBits(%v): got negative result")
+			t.Errorf("SetBits(%v): got negative result", test)
 		}
 
 		bits := nat(z.Bits())