diff --git a/src/angle.cpp b/src/angle.cpp
index 62cb006..adc8b8c 100644
--- a/src/angle.cpp
+++ b/src/angle.cpp
@@ -46,30 +46,12 @@ double deg_to_rad(double value)
 
 double delta_deg(double value1, double value2)
 {
-  double result;
-  double temp = value1 - value2;
-
-  if (abs(temp) > 180) {
-    result = -1 * temp;
-  } else {
-    result = temp;
-  }
-
-  return wrap_deg(result);
+  return wrap_deg(value2 - value1);
 }
 
 double delta_rad(double value1, double value2)
 {
-  double result;
-  double temp = value1 - value2;
-
-  if (abs(temp) > keisan::pi) {
-    result = -1 * temp;
-  } else {
-    result = temp;
-  }
-
-  return wrap_rad(result);
+  return wrap_rad(value2 - value1);
 }
 
 }  // namespace keisan
diff --git a/test/angle_test.cpp b/test/angle_test.cpp
index 68c8507..31e6354 100644
--- a/test/angle_test.cpp
+++ b/test/angle_test.cpp
@@ -63,11 +63,11 @@ TEST(DegToRadTest, ConversionTest) {
 
 TEST(DeltaDegTest, OverflowTest) {
   ASSERT_DOUBLE_EQ(
-    keisan::delta_deg(30.0, -40.0),
+    keisan::delta_deg(-30.0, 40.0),
     70.0);
 
   ASSERT_DOUBLE_EQ(
-    keisan::delta_deg(-30.0, 40.0),
+    keisan::delta_deg(30.0, -40.0),
     -70.0);
 
   ASSERT_DOUBLE_EQ(
@@ -82,11 +82,11 @@ TEST(DeltaDegTest, OverflowTest) {
 TEST(DeltaRadTest, OverflowTest)
 {
   ASSERT_DOUBLE_EQ(
-    keisan::delta_rad(keisan::pi * 0.1, keisan::pi * -0.3),
+    keisan::delta_rad(keisan::pi * -0.1, keisan::pi * 0.3),
     keisan::pi * 0.4);
 
   ASSERT_DOUBLE_EQ(
-    keisan::delta_rad(keisan::pi * -0.1, keisan::pi * 0.3),
+    keisan::delta_rad(keisan::pi * 0.1, keisan::pi * -0.3),
     keisan::pi * -0.4);
 
   ASSERT_DOUBLE_EQ(