diff --git a/src/action_node.cpp b/src/action_node.cpp
index 77f1f440b..8e47ad940 100644
--- a/src/action_node.cpp
+++ b/src/action_node.cpp
@@ -14,6 +14,11 @@
 #define MINICORO_IMPL
 #include "behaviortree_cpp/action_node.h"
 
+// minicoro.h includes this inside extern "C": include it first, at global scope.
+#ifdef __EMSCRIPTEN__
+#include <emscripten/fiber.h>
+#endif
+
 #include "minicoro.h"
 
 #include <iostream>