diff --git a/algo/base/yaml/BaseTypes.h b/algo/base/yaml/BaseTypes.h
index 1a58763e2b5b016f30574883a80b90e396ded45e..1743aace818e77ba8ad33993711f79111a7e1b86 100644
--- a/algo/base/yaml/BaseTypes.h
+++ b/algo/base/yaml/BaseTypes.h
@@ -1,6 +1,8 @@
 /* Copyright (C) 2023 FIAS Frankfurt Institute for Advanced Studies, Frankfurt / Main
    SPDX-License-Identifier: GPL-3.0-only
    Authors: Felix Weiglhofer [committer] */
+#ifndef CBM_YAML_BASETYPES_H
+#define CBM_YAML_BASETYPES_H
 #pragma once
 
 #include "Definitions.h"
@@ -139,3 +141,4 @@ namespace cbm::algo::yaml
 
 
 }  // namespace cbm::algo::yaml
+#endif  // CBM_YAML_BASETYPES_H
diff --git a/algo/base/yaml/Property.h b/algo/base/yaml/Property.h
index 644c77bfdc9b284f49180455aad534970f0db23d..223a978542779a9499bb7f95d5b273f5238f4d5c 100644
--- a/algo/base/yaml/Property.h
+++ b/algo/base/yaml/Property.h
@@ -1,6 +1,8 @@
 /* Copyright (C) 2023 FIAS Frankfurt Institute for Advanced Studies, Frankfurt / Main
    SPDX-License-Identifier: GPL-3.0-only
    Authors: Felix Weiglhofer [committer] */
+#ifndef CBM_YAML_PROPERTY_H
+#define CBM_YAML_PROPERTY_H
 #pragma once
 
 #include "Definitions.h"
@@ -82,3 +84,5 @@ namespace cbm::algo::yaml
 #define CBM_YAML_MERGE_PROPERTY()                                                                                      \
  public:                                                                                                               \
   static constexpr bool MergeProperty = true
+
+#endif  // CBM_YAML_PROPERTY_H
diff --git a/algo/base/yaml/Yaml.h b/algo/base/yaml/Yaml.h
index 56bd2246e06bf0e067009d85e8091cf1bf892785..e5dfa3d33adbe63720b129d52f762028b4f00840 100644
--- a/algo/base/yaml/Yaml.h
+++ b/algo/base/yaml/Yaml.h
@@ -1,6 +1,8 @@
 /* Copyright (C) 2023 FIAS Frankfurt Institute for Advanced Studies, Frankfurt / Main
    SPDX-License-Identifier: GPL-3.0-only
    Authors: Felix Weiglhofer [committer] */
+#ifndef CBM_YAML_YAML_H
+#define CBM_YAML_YAML_H
 #pragma once
 
 #include "Definitions.h"
@@ -305,3 +307,5 @@ namespace cbm::algo::yaml
 #define CBM_YAML_INSTANTIATE(type)                                                                                     \
   template type cbm::algo::yaml::Read<type>(const YAML::Node& node);                                                   \
   template std::string cbm::algo::yaml::Dump::operator()<type>(const type& value, int floatPrecision);
+
+#endif  // CBM_YAML_YAML_H