diff --git a/passes/cmds/linux_perf.cc b/passes/cmds/linux_perf.cc
index 967ccd2f8..2b75a3a79 100644
--- a/passes/cmds/linux_perf.cc
+++ b/passes/cmds/linux_perf.cc
@@ -28,6 +28,7 @@ USING_YOSYS_NAMESPACE
 PRIVATE_NAMESPACE_BEGIN
 
 #ifdef __linux__
+#include <unistd.h>
 struct LinuxPerf : public Pass {
 	LinuxPerf() : Pass("linux_perf", "turn linux perf recording off or on") {
 		internal();