diff --git a/include/Core.h b/include/Core.h
index d6f16c5..7a54094 100644
--- a/include/Core.h
+++ b/include/Core.h
@@ -316,9 +316,11 @@ struct GraphManager {
 };
 
 }; // namespace CudaTools
+#endif // CUDATOOLS_H
 
 #ifdef CUDATOOLS_IMPLEMENTATION
-
+#ifndef __CUDATOOLS_IMPLEMENTED__
+#define __CUDATOOLS_IMPLEMENTED__
 namespace CudaTools {
 
 //////////////////////
@@ -677,6 +679,5 @@ void GraphManager::joinBranch(const StreamID& orig_stream, const StreamID& branc
 }
 
 };     // namespace CudaTools
+#endif
 #endif // CUDATOOLS_IMPLEMENTATION
-
-#endif // CUDATOOLS_H