diff --git a/src/error-map.h b/src/error-map.h
index 3710b2f..bee3bfb 100644
--- a/src/error-map.h
+++ b/src/error-map.h
@@ -1,5 +1,5 @@
-#ifndef ERROR_MAP_H_
-#define ERROR_MAP_H_
+#ifndef EPOLL_ERROR_MAP_H_
+#define EPOLL_ERROR_MAP_H_
 
 /* clang-format off */
 
@@ -598,4 +598,4 @@
 
 /* clang-format on */
 
-#endif /* ERROR_MAP_H_ */
+#endif /* EPOLL_ERROR_MAP_H_ */
diff --git a/src/error.h b/src/error.h
index e792b10..08defcf 100644
--- a/src/error.h
+++ b/src/error.h
@@ -1,5 +1,5 @@
-#ifndef ERROR_H_
-#define ERROR_H_
+#ifndef EPOLL_ERROR_H_
+#define EPOLL_ERROR_H_
 
 #include <errno.h>
 
@@ -21,4 +21,4 @@ EPOLL_INTERNAL void we_set_win_error(DWORD error);
 
 #define return_error(value, ...) _return_error_helper(__VA_ARGS__ + 0, value)
 
-#endif /* ERROR_H_ */
+#endif /* EPOLL_ERROR_H_ */
diff --git a/src/queue.h b/src/queue.h
index ce30a6d..6b96626 100644
--- a/src/queue.h
+++ b/src/queue.h
@@ -1,5 +1,5 @@
-#ifndef QUEUE_H_
-#define QUEUE_H_
+#ifndef EPOLL_QUEUE_H_
+#define EPOLL_QUEUE_H_
 
 #include <stdbool.h>
 
@@ -31,4 +31,4 @@ EPOLL_INTERNAL void queue_remove(queue_node_t* node);
 EPOLL_INTERNAL bool queue_empty(const queue_t* queue);
 EPOLL_INTERNAL bool queue_enqueued(const queue_node_t* node);
 
-#endif /* QUEUE_H_ */
+#endif /* EPOLL_QUEUE_H_ */
diff --git a/src/reflock-tree.h b/src/reflock-tree.h
index 64df2a3..31628cd 100644
--- a/src/reflock-tree.h
+++ b/src/reflock-tree.h
@@ -1,5 +1,5 @@
-#ifndef REFLOCK_TREE_H_
-#define REFLOCK_TREE_H_
+#ifndef EPOLL_REFLOCK_TREE_H_
+#define EPOLL_REFLOCK_TREE_H_
 
 #include <stdint.h>
 
diff --git a/src/reflock.h b/src/reflock.h
index fb548b4..73938eb 100644
--- a/src/reflock.h
+++ b/src/reflock.h
@@ -1,5 +1,5 @@
-#ifndef REFLOCK_H_
-#define REFLOCK_H_
+#ifndef EPOLL_REFLOCK_H_
+#define EPOLL_REFLOCK_H_
 
 /* The reflock is a special kind of lock that normally prevents a chunk of
  * memory from being freed, but does allow the chunk of memory to eventually be
@@ -34,4 +34,4 @@ EPOLL_INTERNAL void reflock_ref(reflock_t* reflock);
 EPOLL_INTERNAL void reflock_unref(reflock_t* reflock);
 EPOLL_INTERNAL void reflock_unref_and_destroy(reflock_t* reflock);
 
-#endif /* REFLOCK_H_ */
+#endif /* EPOLL_REFLOCK_H_ */
diff --git a/src/tree.h b/src/tree.h
index 27e3122..35d5800 100644
--- a/src/tree.h
+++ b/src/tree.h
@@ -1,5 +1,5 @@
-#ifndef EPOLL_HANDLE_TREE_H_
-#define EPOLL_HANDLE_TREE_H_
+#ifndef EPOLL_TREE_H_
+#define EPOLL_TREE_H_
 
 #include "internal.h"
 #include "rb.h"
@@ -20,4 +20,4 @@ EPOLL_INTERNAL int tree_del(tree_t* tree, tree_node_t* node);
 EPOLL_INTERNAL tree_node_t* tree_find(tree_t* tree, uintptr_t key);
 EPOLL_INTERNAL tree_node_t* tree_root(tree_t* tree);
 
-#endif /* EPOLL_HANDLE_TREE_H_ */
+#endif /* EPOLL_TREE_H_ */