diff --git a/CPUMeter.c b/CPUMeter.c
index 62c9971b..badca940 100644
--- a/CPUMeter.c
+++ b/CPUMeter.c
@@ -42,7 +42,7 @@ static void CPUMeter_updateValues(Meter* this, char* buffer, int size) {
    if (this->pl->settings->showCPUFrequency) {
       double cpuFrequency = this->values[CPU_METER_FREQUENCY];
       char cpuFrequencyBuffer[16];
-      if (cpuFrequency < 0) {
+      if (isnan(cpuFrequency)) {
          xSnprintf(cpuFrequencyBuffer, sizeof(cpuFrequencyBuffer), "N/A");
       } else {
          xSnprintf(cpuFrequencyBuffer, sizeof(cpuFrequencyBuffer), "%.0fMHz", cpuFrequency);
diff --git a/darwin/Platform.c b/darwin/Platform.c
index 1186fe04..129b1cb9 100644
--- a/darwin/Platform.c
+++ b/darwin/Platform.c
@@ -19,6 +19,7 @@ in the source distribution for its full text.
 #include "zfs/ZfsCompressedArcMeter.h"
 #include "DarwinProcessList.h"
 
+#include <math.h>
 #include <stdlib.h>
 
 
@@ -210,7 +211,7 @@ double Platform_setCPUValues(Meter* mtr, int cpu) {
    /* Convert to percent and return */
    total = mtr->values[CPU_METER_NICE] + mtr->values[CPU_METER_NORMAL] + mtr->values[CPU_METER_KERNEL];
 
-   mtr->values[CPU_METER_FREQUENCY] = -1;
+   mtr->values[CPU_METER_FREQUENCY] = NAN;
 
    return CLAMP(total, 0.0, 100.0);
 }
diff --git a/dragonflybsd/Platform.c b/dragonflybsd/Platform.c
index 3b8e1a0d..e4e78e38 100644
--- a/dragonflybsd/Platform.c
+++ b/dragonflybsd/Platform.c
@@ -168,7 +168,7 @@ double Platform_setCPUValues(Meter* this, int cpu) {
    percent = CLAMP(percent, 0.0, 100.0);
    if (isnan(percent)) percent = 0.0;
 
-   v[CPU_METER_FREQUENCY] = -1;
+   v[CPU_METER_FREQUENCY] = NAN;
 
    return percent;
 }
diff --git a/freebsd/Platform.c b/freebsd/Platform.c
index df664ae5..3fc5de31 100644
--- a/freebsd/Platform.c
+++ b/freebsd/Platform.c
@@ -171,7 +171,7 @@ double Platform_setCPUValues(Meter* this, int cpu) {
    percent = CLAMP(percent, 0.0, 100.0);
    if (isnan(percent)) percent = 0.0;
 
-   v[CPU_METER_FREQUENCY] = -1;
+   v[CPU_METER_FREQUENCY] = NAN;
 
    return percent;
 }
diff --git a/linux/LinuxProcessList.c b/linux/LinuxProcessList.c
index 18dda3ed..9f754f19 100644
--- a/linux/LinuxProcessList.c
+++ b/linux/LinuxProcessList.c
@@ -1153,7 +1153,7 @@ static inline double LinuxProcessList_scanCPUFrequency(LinuxProcessList* this) {
 
    for (int i = 0; i <= cpus; i++) {
       CPUData* cpuData = &(this->cpus[i]);
-      cpuData->frequency = -1;
+      cpuData->frequency = NAN;
    }
 
    int numCPUsWithFrequency = 0;
diff --git a/openbsd/Platform.c b/openbsd/Platform.c
index cb162078..bd5ef7ef 100644
--- a/openbsd/Platform.c
+++ b/openbsd/Platform.c
@@ -162,7 +162,7 @@ double Platform_setCPUValues(Meter* this, int cpu) {
       v[CPU_METER_STEAL]   = 0.0;
       v[CPU_METER_GUEST]   = 0.0;
       v[CPU_METER_IOWAIT]  = 0.0;
-      v[CPU_METER_FREQUENCY] = -1;
+      v[CPU_METER_FREQUENCY] = NAN;
       Meter_setItems(this, 8);
       totalPercent = v[0]+v[1]+v[2]+v[3];
    } else {
diff --git a/solaris/Platform.c b/solaris/Platform.c
index 436c9ce9..d3ad1f93 100644
--- a/solaris/Platform.c
+++ b/solaris/Platform.c
@@ -186,7 +186,7 @@ double Platform_setCPUValues(Meter* this, int cpu) {
    percent = CLAMP(percent, 0.0, 100.0);
    if (isnan(percent)) percent = 0.0;
 
-   v[CPU_METER_FREQUENCY] = -1;
+   v[CPU_METER_FREQUENCY] = NAN;
 
    return percent;
 }
diff --git a/unsupported/Platform.c b/unsupported/Platform.c
index 420dfb78..20df3376 100644
--- a/unsupported/Platform.c
+++ b/unsupported/Platform.c
@@ -6,6 +6,8 @@ Released under the GNU GPL, see the COPYING file
 in the source distribution for its full text.
 */
 
+#include <math.h>
+
 #include "Platform.h"
 #include "CPUMeter.h"
 #include "MemoryMeter.h"
@@ -105,7 +107,7 @@ double Platform_setCPUValues(Meter* this, int cpu) {
    (void) cpu;
 
    double* v = this->values;
-   v[CPU_METER_FREQUENCY] = -1;
+   v[CPU_METER_FREQUENCY] = NAN;
 
    return 0.0;
 }