diff --git a/CPUMeter.c b/CPUMeter.c
index 7bc096dbc..90ec520a2 100644
--- a/CPUMeter.c
+++ b/CPUMeter.c
@@ -233,7 +233,7 @@ static void CPUMeter_display(const Object* cast, RichString* out) {
    #endif
 }
 
-static void AllCPUsMeter_getRange(const Meter* this, int* start, int* count) {
+static void AllCPUsMeter_getRange(const Meter* this, unsigned int* start, unsigned int* count) {
    unsigned int cpus = this->host->existingCPUs;
    switch (Meter_name(this)[0]) {
       default:
@@ -252,29 +252,35 @@ static void AllCPUsMeter_getRange(const Meter* this, int* start, int* count) {
    }
 }
 
-static void AllCPUsMeter_updateValues(Meter* this) {
-   CPUMeterData* data = this->meterData;
-   Meter** meters = data->meters;
-   int start, count;
-   AllCPUsMeter_getRange(this, &start, &count);
-   for (int i = 0; i < count; i++)
-      Meter_updateValues(meters[i]);
-}
-
 static void CPUMeterCommonInit(Meter* this) {
-   int start, count;
+   unsigned int start, count, prevCount;
    AllCPUsMeter_getRange(this, &start, &count);
 
    CPUMeterData* data = this->meterData;
    if (!data) {
       data = xCalloc(1, sizeof(CPUMeterData));
-      data->cpus = this->host->existingCPUs;
-      data->meters = count ? xCalloc(count, sizeof(Meter*)) : NULL;
+      data->cpus = 0;   /* no meters allocated yet */
+      data->meters = NULL;
       this->meterData = data;
    }
 
+   prevCount = data->cpus;
+   if (count != prevCount) {
+      /* free meters for CPUs that are no longer in range */
+      for (unsigned int i = count; i < prevCount; i++)
+         Meter_delete((Object*)data->meters[i]);
+
+      if (count > 0) {
+         data->meters = xReallocArrayZero(data->meters, prevCount, count, sizeof(Meter*));
+      } else {
+         free(data->meters);
+         data->meters = NULL;
+      }
+      data->cpus = count;
+   }
+
    Meter** meters = data->meters;
-   for (int i = 0; i < count; i++) {
+   for (unsigned int i = 0; i < count; i++) {
       if (!meters[i])
          meters[i] = Meter_new(this->host, start + i + 1, (const MeterClass*) Class(CPUMeter));
 
@@ -282,17 +288,32 @@ static void CPUMeterCommonInit(Meter* this) {
    }
 }
 
-static void CPUMeterCommonUpdateMode(Meter* this, MeterModeId mode, int ncol) {
+static void AllCPUsMeter_updateValues(Meter* this) {
+   CPUMeterData* data = this->meterData;
+   unsigned int start, count;
+   AllCPUsMeter_getRange(this, &start, &count);
+   /* Reinit if the number of CPUs changed (e.g. hot-plug) */
+   if (count != data->cpus)
+      CPUMeterCommonInit(this);
+   data = this->meterData;
+   Meter** meters = data->meters;
+   for (unsigned int i = 0; i < count; i++)
+      Meter_updateValues(meters[i]);
+}
+
+static void CPUMeterCommonUpdateMode(Meter* this, MeterModeId mode, unsigned int ncol) {
+   /* Reinit first in case the CPU count changed since last init */
+   CPUMeterCommonInit(this);
    CPUMeterData* data = this->meterData;
    Meter** meters = data->meters;
    this->mode = mode;
-   int start, count;
+   unsigned int start, count;
    AllCPUsMeter_getRange(this, &start, &count);
    if (!count) {
       this->h = 1;
       return;
    }
-   for (int i = 0; i < count; i++) {
+   for (unsigned int i = 0; i < count; i++) {
       Meter_setMode(meters[i], mode);
    }
    int h = meters[0]->h;
@@ -303,9 +324,7 @@ static void CPUMeterCommonUpdateMode(Meter* this, MeterModeId mode, int ncol) {
 static void AllCPUsMeter_done(Meter* this) {
    CPUMeterData* data = this->meterData;
    Meter** meters = data->meters;
-   int start, count;
-   AllCPUsMeter_getRange(this, &start, &count);
-   for (int i = 0; i < count; i++)
+   for (unsigned int i = 0; i < data->cpus; i++)
       Meter_delete((Object*)meters[i]);
    free(data->meters);
    free(data);
@@ -327,17 +346,18 @@ static void OctoColCPUsMeter_updateMode(Meter* this, MeterModeId mode) {
    CPUMeterCommonUpdateMode(this, mode, 8);
 }
 
-static void CPUMeterCommonDraw(Meter* this, int x, int y, int w, int ncol) {
+static void CPUMeterCommonDraw(Meter* this, int x, int y, int w, unsigned int ncol) {
    CPUMeterData* data = this->meterData;
    Meter** meters = data->meters;
-   int start, count;
+   unsigned int start, count;
    AllCPUsMeter_getRange(this, &start, &count);
-   int colwidth = w / ncol;
-   int diff = w % ncol;
-   int nrows = (count + ncol - 1) / ncol;
-   for (int i = 0; i < count; i++) {
-      int d = (i / nrows) > diff ? diff : (i / nrows); // dynamic spacer
-      int xpos = x + ((i / nrows) * colwidth) + d;
+   int colwidth = w / (int)ncol;
+   int diff = w % (int)ncol;
+   unsigned int nrows = (count + ncol - 1) / ncol;
+   for (unsigned int i = 0; i < count; i++) {
+      unsigned int col = i / nrows;
+      int d = (int)col > diff ? diff : (int)col; // dynamic spacer
+      int xpos = x + ((int)col * colwidth) + d;
       int ypos = y + ((i % nrows) * meters[0]->h);
       meters[i]->draw(meters[i], xpos, ypos, colwidth);
    }
@@ -359,9 +379,9 @@ static void OctoColCPUsMeter_draw(Meter* this, int x, int y, int w) {
 static void SingleColCPUsMeter_draw(Meter* this, int x, int y, int w) {
    CPUMeterData* data = this->meterData;
    Meter** meters = data->meters;
-   int start, count;
+   unsigned int start, count;
    AllCPUsMeter_getRange(this, &start, &count);
-   for (int i = 0; i < count; i++) {
+   for (unsigned int i = 0; i < count; i++) {
       meters[i]->draw(meters[i], x, y, w);
       y += meters[i]->h;
    }