diff --git a/run.c b/run.c
index 02cc877..4ff9e5d 100644
--- a/run.c
+++ b/run.c
@@ -20,6 +20,11 @@ $ ./run
     #include <unistd.h>
     #include <sys/mman.h>
 #endif
+
+#ifdef _OPENMP
+#include <omp.h>
+#endif
+
 // ----------------------------------------------------------------------------
 // Transformer and RunState structs, and related memory management