diff --git a/src/TriangleChecker.java b/src/TriangleChecker.java
index 2378746..aa6005a 100644
--- a/src/TriangleChecker.java
+++ b/src/TriangleChecker.java
@@ -54,6 +54,7 @@ public class TriangleChecker {
       if(a==b || b==c|| a==c) {
         //Gleichseitiges Dreieck
         if (a == b && b == c && a == c) return TriangleType.EQUILATERAL;
+
         return TriangleType.ISOSCELES;
       }
       return TriangleType.NORMAL;
diff --git a/test/TriangleCheckerTest.java b/test/TriangleCheckerTest.java
index 776699c..b1aac6d 100644
--- a/test/TriangleCheckerTest.java
+++ b/test/TriangleCheckerTest.java
@@ -16,6 +16,72 @@ public class TriangleCheckerTest {
 
         // Assert
         assertEquals(TriangleChecker.TriangleType.NORMAL, type);
+
+        // Arrange
+        a = -2;
+        b = 3;
+        c = 4;
+
+        // Act
+        type = TriangleChecker.checkTriangle(a, b, c);
+
+        // Assert
+        assertEquals(TriangleChecker.TriangleType.NONE, type);
+
+        // Arrange
+        a = 2;
+        b = -3;
+        c = 4;
+
+        // Act
+        type = TriangleChecker.checkTriangle(a, b, c);
+
+        // Assert
+        assertEquals(TriangleChecker.TriangleType.NONE, type);
+
+        // Arrange
+        a = 2;
+        b = 3;
+        c = -4;
+
+        // Act
+        type = TriangleChecker.checkTriangle(a, b, c);
+
+        // Assert
+        assertEquals(TriangleChecker.TriangleType.NONE, type);
+
+        // Arrange
+        a = 2;
+        b = 3;
+        c = 10;
+
+        // Act
+        type = TriangleChecker.checkTriangle(a, b, c);
+
+        // Assert
+        assertEquals(TriangleChecker.TriangleType.NONE, type);
+
+        // Arrange
+        a = 10;
+        b = 3;
+        c = 4;
+
+        // Act
+        type = TriangleChecker.checkTriangle(a, b, c);
+
+        // Assert
+        assertEquals(TriangleChecker.TriangleType.NONE, type);
+
+        // Arrange
+        a = 2;
+        b = 10;
+        c = 4;
+
+        // Act
+        type = TriangleChecker.checkTriangle(a, b, c);
+
+        // Assert
+        assertEquals(TriangleChecker.TriangleType.NONE, type);
     }
 
     @Test