diff --git a/libyul/optimiser/CommonSwitchCasePrefixMover.cpp b/libyul/optimiser/CommonSwitchCasePrefixMover.cpp
index 94e498c71..924f66c5f 100644
--- a/libyul/optimiser/CommonSwitchCasePrefixMover.cpp
+++ b/libyul/optimiser/CommonSwitchCasePrefixMover.cpp
@@ -68,15 +68,16 @@ namespace
 template<typename Container>
 auto eraseFirst(Container& _container) { return _container.erase(begin(_container)); }
 
-optional<Statement> tryExtractFirstStatement(Identifier const* _identifier, vector<Case>& _cases)
+optional<Statement> tryExtractFirstStatement(Identifier const* _switchExpressionAsIdentifier, vector<Case>& _cases)
 {
+	yulAssert(!_cases.empty() && !_cases.front().body.statements.empty(), "");
 	Statement& referenceStatement = _cases.front().body.statements.front();
 
-	if (_identifier)
+	if (_switchExpressionAsIdentifier)
 	{
 		Assignments assignments;
 		visit(assignments, referenceStatement);
-		if (assignments.names().count(_identifier->name))
+		if (assignments.names().count(_switchExpressionAsIdentifier->name))
 			return nullopt;
 	}
 
@@ -136,11 +137,11 @@ void CommonSwitchCasePrefixMover::operator()(Block& _block)
 
 				Identifier const* identifier = std::get_if<Identifier>(switchStatement->expression.get());
 				if (!identifier && !holds_alternative<Literal>(*switchStatement->expression.get()))
-					return {};
+					return nullopt;
 
 				// We need to be able to tell how the default case behaves.
-				if (switchStatement->cases.back().value)
-					return {};
+				if (switchStatement->cases.back().value != nullptr)
+					return nullopt;
 
 				vector<Statement> result;
 				while (!switchStatement->cases.front().body.statements.empty())
@@ -155,7 +156,7 @@ void CommonSwitchCasePrefixMover::operator()(Block& _block)
 					return result;
 				}
 			}
-			return {};
+			return nullopt;
 		}
 	);
 }
diff --git a/test/libyul/yulOptimizerTests/commonSwitchCasePrefixMover/assignToExpression.yul b/test/libyul/yulOptimizerTests/commonSwitchCasePrefixMover/assignToExpression.yul
index dcce7f3d9..c976bd379 100644
--- a/test/libyul/yulOptimizerTests/commonSwitchCasePrefixMover/assignToExpression.yul
+++ b/test/libyul/yulOptimizerTests/commonSwitchCasePrefixMover/assignToExpression.yul
@@ -1,12 +1,12 @@
 {
-  let x := calldataload(0)
-  switch x
-  case 0 {
-    x := calldataload(1)
-  }
-  default {
-    x := calldataload(1)
-  }
+    let x := calldataload(0)
+    switch x
+    case 0 {
+        x := calldataload(1)
+    }
+    default {
+        x := calldataload(1)
+    }
 }
 // ----
 // step: commonSwitchCasePrefixMover
diff --git a/test/libyul/yulOptimizerTests/commonSwitchCasePrefixMover/builtinExpression.yul b/test/libyul/yulOptimizerTests/commonSwitchCasePrefixMover/builtinExpression.yul
index fb65a472a..d71d8ff32 100644
--- a/test/libyul/yulOptimizerTests/commonSwitchCasePrefixMover/builtinExpression.yul
+++ b/test/libyul/yulOptimizerTests/commonSwitchCasePrefixMover/builtinExpression.yul
@@ -1,25 +1,25 @@
 {
-  switch mload(0)
-  case 0 {
-    sstore(1, 0)
-  }
-  default {
-    sstore(1, 0)
-  }
-  switch msize()
-  case 0 {
-    sstore(1, 0)
-  }
-  default {
-    sstore(1, 0)
-  }
-  switch sload(0)
-  case 0 {
-    sstore(1, 0)
-  }
-  default {
-    sstore(1, 0)
-  }
+    switch mload(0)
+    case 0 {
+        sstore(1, 0)
+    }
+    default {
+        sstore(1, 0)
+    }
+    switch msize()
+    case 0 {
+        sstore(1, 0)
+    }
+    default {
+        sstore(1, 0)
+    }
+    switch sload(0)
+    case 0 {
+        sstore(1, 0)
+    }
+    default {
+        sstore(1, 0)
+    }
 }
 // ----
 // step: commonSwitchCasePrefixMover
diff --git a/test/libyul/yulOptimizerTests/commonSwitchCasePrefixMover/forLoop.yul b/test/libyul/yulOptimizerTests/commonSwitchCasePrefixMover/forLoop.yul
index 58b28fdf3..688b98dc9 100644
--- a/test/libyul/yulOptimizerTests/commonSwitchCasePrefixMover/forLoop.yul
+++ b/test/libyul/yulOptimizerTests/commonSwitchCasePrefixMover/forLoop.yul
@@ -1,20 +1,20 @@
 {
-  let x := calldataload(0)
-  switch x
-  case 0 {
-    for { let a := 0 } lt(a, 42) { a := add(a, 1) } {
-      let b := 23
-      sstore(add(b, a), a)
+    let x := calldataload(0)
+    switch x
+    case 0 {
+        for { let a := 0 } lt(a, 42) { a := add(a, 1) } {
+            let b := 23
+            sstore(add(b, a), a)
+        }
+        sstore(0, 23)
     }
-    sstore(0, 23)
-  }
-  default {
-    for { let b := 0 } lt(b, 42) { b := add(b, 1) } {
-      let c := 23
-      sstore(add(c, b), b)
+    default {
+        for { let b := 0 } lt(b, 42) { b := add(b, 1) } {
+            let c := 23
+            sstore(add(c, b), b)
+        }
+        sstore(0, 32)
     }
-    sstore(0, 32)
-  }
 }
 // ----
 // step: commonSwitchCasePrefixMover
diff --git a/test/libyul/yulOptimizerTests/commonSwitchCasePrefixMover/nested.yul b/test/libyul/yulOptimizerTests/commonSwitchCasePrefixMover/nested.yul
index 9b3961486..ab1ac48d8 100644
--- a/test/libyul/yulOptimizerTests/commonSwitchCasePrefixMover/nested.yul
+++ b/test/libyul/yulOptimizerTests/commonSwitchCasePrefixMover/nested.yul
@@ -1,13 +1,13 @@
 {
-  let a := calldataload(42)
-  switch a
-  case 0 {
-    let b := calldataload(23)
-    switch b
-    case 0 { sstore(0, 1) }
-    default { sstore(0, 1) }
-  }
-  default { sstore(1, 2) }
+    let a := calldataload(42)
+    switch a
+    case 0 {
+        let b := calldataload(23)
+        switch b
+        case 0 { sstore(0, 1) }
+        default { sstore(0, 1) }
+    }
+    default { sstore(1, 2) }
 }
 // ----
 // step: commonSwitchCasePrefixMover
diff --git a/test/libyul/yulOptimizerTests/commonSwitchCasePrefixMover/sstoreExpression.yul b/test/libyul/yulOptimizerTests/commonSwitchCasePrefixMover/sstoreExpression.yul
index a38dbec1d..1692cfb25 100644
--- a/test/libyul/yulOptimizerTests/commonSwitchCasePrefixMover/sstoreExpression.yul
+++ b/test/libyul/yulOptimizerTests/commonSwitchCasePrefixMover/sstoreExpression.yul
@@ -1,17 +1,17 @@
 {
-  function f() -> x {
-    x := calldataload(0)
-    sstore(0, 42)
-  }
-  switch f()
-  case 0 {
-    let x := sload(0)
-    sstore(1, x)
-  }
-  default {
-    let x := sload(0)
-    sstore(1, x)
-  }
+    function f() -> x {
+        x := calldataload(0)
+        sstore(0, 42)
+    }
+    switch f()
+    case 0 {
+        let x := sload(0)
+        sstore(1, x)
+    }
+    default {
+        let x := sload(0)
+        sstore(1, x)
+    }
 }
 // ----
 // step: commonSwitchCasePrefixMover
diff --git a/test/libyul/yulOptimizerTests/commonSwitchCasePrefixMover/stub.yul b/test/libyul/yulOptimizerTests/commonSwitchCasePrefixMover/stub.yul
index 9fdb9cef2..c954e363f 100644
--- a/test/libyul/yulOptimizerTests/commonSwitchCasePrefixMover/stub.yul
+++ b/test/libyul/yulOptimizerTests/commonSwitchCasePrefixMover/stub.yul
@@ -1,16 +1,16 @@
 {
-  let x := calldataload(0)
-  switch x
-  case 0 {
-    sstore(0, 1)
-    sstore(1, 2)
-    sstore(2, 3)
-  }
-  default {
-    sstore(0, 1)
-    sstore(1, 2)
-    sstore(2, 4)
-  }
+    let x := calldataload(0)
+    switch x
+    case 0 {
+        sstore(0, 1)
+        sstore(1, 2)
+        sstore(2, 3)
+    }
+    default {
+        sstore(0, 1)
+        sstore(1, 2)
+        sstore(2, 4)
+    }
 }
 // ----
 // step: commonSwitchCasePrefixMover
diff --git a/test/libyul/yulOptimizerTests/commonSwitchCasePrefixMover/varDecl.yul b/test/libyul/yulOptimizerTests/commonSwitchCasePrefixMover/varDecl.yul
index 54ec567d9..442056a81 100644
--- a/test/libyul/yulOptimizerTests/commonSwitchCasePrefixMover/varDecl.yul
+++ b/test/libyul/yulOptimizerTests/commonSwitchCasePrefixMover/varDecl.yul
@@ -1,18 +1,18 @@
 {
-  let x := calldataload(0)
-  switch x
-  case 0 {
-    sstore(0, 23)
-    let a := calldataload(42)
-    sstore(1, a)
-    sstore(2, sub(a, 2))
-  }
-  default {
-    sstore(0, 23)
-    let b := calldataload(42)
-    sstore(1, b)
-    sstore(2, sub(b, 1))
-  }
+    let x := calldataload(0)
+    switch x
+    case 0 {
+        sstore(0, 23)
+        let a := calldataload(42)
+        sstore(1, a)
+        sstore(2, sub(a, 2))
+    }
+    default {
+        sstore(0, 23)
+        let b := calldataload(42)
+        sstore(1, b)
+        sstore(2, sub(b, 1))
+    }
 }
 // ----
 // step: commonSwitchCasePrefixMover