diff --git a/assert/assertions.go b/assert/assertions.go
index 44b854d..d4b4bef 100644
--- a/assert/assertions.go
+++ b/assert/assertions.go
@@ -1527,6 +1527,9 @@ func InEpsilon(t TestingT, expected, actual interface{}, epsilon float64, msgAnd
 	if err != nil {
 		return Fail(t, err.Error(), msgAndArgs...)
 	}
+	if math.IsNaN(actualEpsilon) {
+		return Fail(t, "relative error is NaN", msgAndArgs...)
+	}
 	if actualEpsilon > epsilon {
 		return Fail(t, fmt.Sprintf("Relative error is too high: %#v (expected)\n"+
 			"        < %#v (actual)", epsilon, actualEpsilon), msgAndArgs...)
diff --git a/assert/assertions_test.go b/assert/assertions_test.go
index e158688..848a5d8 100644
--- a/assert/assertions_test.go
+++ b/assert/assertions_test.go
@@ -1986,6 +1986,14 @@ func TestInEpsilon(t *testing.T) {
 		{math.NaN(), 0, 1},
 		{0, math.NaN(), 1},
 		{0, 0, math.NaN()},
+		{math.Inf(1), 1, 1},
+		{math.Inf(-1), 1, 1},
+		{1, math.Inf(1), 1},
+		{1, math.Inf(-1), 1},
+		{math.Inf(1), math.Inf(1), 1},
+		{math.Inf(1), math.Inf(-1), 1},
+		{math.Inf(-1), math.Inf(1), 1},
+		{math.Inf(-1), math.Inf(-1), 1},
 	}
 
 	for _, tc := range cases {