diff --git a/src/rt/core/builtin.cc b/src/rt/core/builtin.cc
index 4810b02..5dae61d 100644
--- a/src/rt/core/builtin.cc
+++ b/src/rt/core/builtin.cc
@@ -103,6 +103,11 @@ namespace rt::core
 
       return std::nullopt;
     });
+
+    add_builtin("unreachable", [](auto, auto, auto) {
+      ui::error("this method should never be called");
+      return std::nullopt;
+    });
   }
 
   void init_builtins(ui::UI* ui)
diff --git a/tests/exprs/ifs.vpy b/tests/exprs/ifs.vpy
index 236dd24..41add39 100644
--- a/tests/exprs/ifs.vpy
+++ b/tests/exprs/ifs.vpy
@@ -5,30 +5,34 @@ a["self"] = a
 f = {}
 f.a = a
 
+# Check if with else (This should be true)
 if a == f.a:
     b = f.a
     c = {}
+    # Check empty lines in blocks:
 
     drop b
     drop c
 else:
+    # Check parsing nested if's
     if f.b == None:
-        e = {}
-        drop e
+        unreachable()
 
     else:
-        d = {}
-        drop d
+        unreachable()
 
+# Check identifier as the condition
 cond = f.a != a
 if cond:
-    dummy = "created"
+    unreachable()
 
+# Check function call as the condition
 def check():
     c = False
+    # Check return condition result
     return c == True
 if check():
-    this = "is false"
+    unreachable()
 
 drop a
 drop f
diff --git a/tests/exprs/while.vpy b/tests/exprs/while.vpy
index de922c7..968a1a0 100644
--- a/tests/exprs/while.vpy
+++ b/tests/exprs/while.vpy
@@ -7,32 +7,32 @@ obj = lst
 while obj != null:
     obj = obj.next
 
-# Identifiers
+# Check identifiers in the condition
 cond = False
 while cond == True:
-    never = "mind"
+    unreachable()
 while cond:
-    never = "mind"
+    unreachable()
 
-# Fields
+# Check field access in the condition
 x = {}
 x.bool = False
 while x.bool == True:
-    never = "mind"
+    unreachable()
 while x.bool:
-    never = "mind"
+    unreachable()
 
-# Function
+# Check function calls in the condition
 def bool(self):
     return False
 while bool({}) == True:
-    never = "mind"
+    unreachable()
 while bool({}):
-    never = "mind"
+    unreachable()
 
-# Method condition
+# Check method calls in the condition
 x.bool = bool
 while x.bool() == True:
-    never = "mind"
+    unreachable()
 while x.bool():
-    never = "mind"
+    unreachable()