diff --git a/libsolc/libsolc.h b/libsolc/libsolc.h
index 4b0ec6398..b58ee8053 100644
--- a/libsolc/libsolc.h
+++ b/libsolc/libsolc.h
@@ -20,6 +20,8 @@
  * Public compiler API.
  */
 
+#pragma once
+
 #include <stdbool.h>
 
 #ifdef __cplusplus
diff --git a/libsolidity/codegen/ExpressionCompiler.h b/libsolidity/codegen/ExpressionCompiler.h
index 2bfaab43b..e9345ece2 100644
--- a/libsolidity/codegen/ExpressionCompiler.h
+++ b/libsolidity/codegen/ExpressionCompiler.h
@@ -21,6 +21,8 @@
  * Solidity AST to EVM bytecode compiler for expressions.
  */
 
+#pragma once
+
 #include <functional>
 #include <memory>
 #include <boost/noncopyable.hpp>
diff --git a/libyul/backends/evm/EVMCodeTransform.h b/libyul/backends/evm/EVMCodeTransform.h
index 28ef4e457..7be6f892c 100644
--- a/libyul/backends/evm/EVMCodeTransform.h
+++ b/libyul/backends/evm/EVMCodeTransform.h
@@ -18,6 +18,8 @@
  * Common code generator for translating Yul / inline assembly to EVM and EVM1.5.
  */
 
+#pragma once
+
 #include <libyul/backends/evm/EVMAssembly.h>
 
 #include <libyul/backends/evm/EVMDialect.h>
diff --git a/libyul/backends/evm/EVMObjectCompiler.h b/libyul/backends/evm/EVMObjectCompiler.h
index 057521a89..9325e0722 100644
--- a/libyul/backends/evm/EVMObjectCompiler.h
+++ b/libyul/backends/evm/EVMObjectCompiler.h
@@ -18,6 +18,7 @@
  * Compiler that transforms Yul Objects to EVM bytecode objects.
  */
 
+#pragma once
 
 namespace yul
 {