diff --git a/utils/math/safe_math_test.go b/utils/math/safe_math_test.go
index c8428b5..47f65f9 100644
--- a/utils/math/safe_math_test.go
+++ b/utils/math/safe_math_test.go
@@ -10,6 +10,28 @@ import (
 
 const maxUint64 uint64 = math.MaxUint64
 
+func TestMax64(t *testing.T) {
+	actual := Max64(0, maxUint64)
+	if actual != maxUint64 {
+		t.Fatalf("Expected %d, got %d", maxUint64, actual)
+	}
+	actual = Max64(maxUint64, 0)
+	if actual != maxUint64 {
+		t.Fatalf("Expected %d, got %d", maxUint64, actual)
+	}
+}
+
+func TestMin64(t *testing.T) {
+	actual := Min64(0, maxUint64)
+	if actual != 0 {
+		t.Fatalf("Expected %d, got %d", 0, actual)
+	}
+	actual = Min64(maxUint64, 0)
+	if actual != 0 {
+		t.Fatalf("Expected %d, got %d", 0, actual)
+	}
+}
+
 func TestAdd64(t *testing.T) {
 	sum, err := Add64(0, maxUint64)
 	if err != nil {
@@ -51,6 +73,20 @@ func TestAdd64(t *testing.T) {
 	}
 }
 
+func TestSub64(t *testing.T) {
+	actual, err := Sub64(2, 1)
+	if err != nil {
+		t.Fatalf("Sub64 failed unexpectedly")
+	} else if actual != 1 {
+		t.Fatalf("Expected %d, got %d", 1, actual)
+	}
+
+	_, err = Sub64(1, 2)
+	if err == nil {
+		t.Fatalf("Sub64 did not fail in the manner expected")
+	}
+}
+
 func TestMul64(t *testing.T) {
 	if prod, err := Mul64(maxUint64, 0); err != nil {
 		t.Fatalf("Mul64 failed unexpectedly")
@@ -68,3 +104,15 @@ func TestMul64(t *testing.T) {
 		t.Fatalf("Mul64 overflowed")
 	}
 }
+
+func TestDiff64(t *testing.T) {
+	actual := Diff64(0, maxUint64)
+	if actual != maxUint64 {
+		t.Fatalf("Expected %d, got %d", maxUint64, actual)
+	}
+
+	actual = Diff64(maxUint64, 0)
+	if actual != maxUint64 {
+		t.Fatalf("Expected %d, got %d", maxUint64, actual)
+	}
+}