--- a/tools/power/rapl.cpp
+++ b/tools/power/rapl.cpp
@@ -513,18 +513,18 @@ public:
 
     struct perf_event_attr attr;
     memset(&attr, 0, sizeof(attr));
     attr.type = aType;
     attr.size = uint32_t(sizeof(attr));
     attr.config = config;
 
     // Measure all processes/threads. The specified CPU doesn't matter.
-    mFd = perf_event_open(&attr, /* pid = */ -1, /* cpu = */ 0,
-                          /* group_fd = */ -1, /* flags = */ 0);
+    mFd = perf_event_open(&attr, /* aPid = */ -1, /* aCpu = */ 0,
+                          /* aGroupFd = */ -1, /* aFlags = */ 0);
     if (mFd < 0) {
       Abort("perf_event_open() failed\n"
             "- Did you run as root (e.g. with |sudo|) or set\n"
             "  /proc/sys/kernel/perf_event_paranoid to 0, as required?");
     }
 
     mPrevTicks = 0;
   }