diff --git a/assert/assertions.go b/assert/assertions.go
index 4c03834..c632bc7 100644
--- a/assert/assertions.go
+++ b/assert/assertions.go
@@ -886,6 +886,8 @@ func toFloat(x interface{}) (float64, bool) {
 		xf = float64(xn)
 	case float64:
 		xf = float64(xn)
+	case time.Duration:
+		xf = float64(xn)
 	default:
 		xok = false
 	}
diff --git a/assert/assertions_test.go b/assert/assertions_test.go
index cd67ee6..bb2b59f 100644
--- a/assert/assertions_test.go
+++ b/assert/assertions_test.go
@@ -1045,6 +1045,7 @@ func TestInEpsilon(t *testing.T) {
 		{uint64(100), uint8(101), 0.01},
 		{0.1, -0.1, 2},
 		{0.1, 0, 2},
+		{time.Second, time.Second + time.Millisecond, 0.002},
 	}
 
 	for _, tc := range cases {
@@ -1063,6 +1064,7 @@ func TestInEpsilon(t *testing.T) {
 		{2.1, "bla-bla", 0},
 		{0.1, -0.1, 1.99},
 		{0, 0.1, 2}, // expected must be different to zero
+		{time.Second, time.Second + 10*time.Millisecond, 0.002},
 	}
 
 	for _, tc := range cases {