diff --git a/Implicit.hpp b/Implicit.hpp
index 94f3bd8..8a45776 100644
--- a/Implicit.hpp
+++ b/Implicit.hpp
@@ -1,3 +1,5 @@
+#pragma once
+
 class ImplicitSurface {
     public:
         virtual double operator() (double x, double y, double z);
diff --git a/Mesh.hpp b/Mesh.hpp
index 63ea5f8..e46c127 100644
--- a/Mesh.hpp
+++ b/Mesh.hpp
@@ -2,6 +2,8 @@
  * Defines a mesh, ready to be OpenGL-rendered
  **/
 
+#pragma once
+
 #include <vector>
 #include <unordered_map>
 #include <cstddef>  // size_t
diff --git a/common_structures.hpp b/common_structures.hpp
index b38e2d6..fd6d841 100644
--- a/common_structures.hpp
+++ b/common_structures.hpp
@@ -2,6 +2,8 @@
  * Defines a few widely used, widely spread structures. Imported pervasively.
  **/
 
+#pragma once
+
 #include <functional>  // Hash
 #include <vector>
 #include <cassert>
diff --git a/render/GlutRender.hpp b/render/GlutRender.hpp
index 699a26a..688a1d6 100644
--- a/render/GlutRender.hpp
+++ b/render/GlutRender.hpp
@@ -1,5 +1,7 @@
 /** The most basic renderer — a stupid glut application */
 
+#pragma once
+
 #include "../Mesh.hpp"
 #include <set>
 
diff --git a/util/ObjParser.hpp b/util/ObjParser.hpp
index 5fa697b..02ddcb2 100644
--- a/util/ObjParser.hpp
+++ b/util/ObjParser.hpp
@@ -1,5 +1,7 @@
 /** Parses .obj mesh files, outputting a `Mesh` */
 
+#pragma once
+
 #include <fstream>
 #include <string>
 #include <stdexcept>