diff --git a/cmd/termshark/termshark.go b/cmd/termshark/termshark.go
index c4b0e60..a0f2695 100644
--- a/cmd/termshark/termshark.go
+++ b/cmd/termshark/termshark.go
@@ -921,11 +921,16 @@ func cmain() int {
 
 	var progCancelTimer *time.Timer
 
+	checkedPcapCache := false
+	checkPcapCacheDuration := 5 * time.Second
+	checkPcapCacheTimer := time.NewTimer(checkPcapCacheDuration)
+
 Loop:
 	for {
 		var finChan <-chan time.Time
 		var tickChan <-chan time.Time
 		var inactivityChan <-chan time.Time
+		var checkPcapCacheChan <-chan time.Time
 		var tcellEvents <-chan tcell.Event
 		var opsChan <-chan gowid.RunFunction
 		var afterRenderEvents <-chan gowid.IAfterRenderEvent
@@ -992,6 +997,10 @@ Loop:
 			inactivityChan = inactivityTimer.C
 		}
 
+		if !checkedPcapCache {
+			checkPcapCacheChan = checkPcapCacheTimer.C
+		}
+
 		// Only process tcell and gowid events if the UI is running.
 		if ui.Running {
 			tcellEvents = app.TCellEvents
@@ -1017,6 +1026,16 @@ Loop:
 
 		select {
 
+		case <-checkPcapCacheChan:
+			// Only check the cache dir if we own it; don't want to delete pcap files
+			// that might be shared with wireshark
+			if termshark.ConfBool("main.use-tshark-temp-for-pcap-cache", false) {
+				log.Infof("Termshark does not own the pcap temp dir %s; skipping size check", termshark.PcapDir())
+			} else {
+				termshark.PrunePcapCache()
+			}
+			checkedPcapCache = true
+
 		case <-inactivityChan:
 			ui.Fin.Activate()
 			app.Redraw()
@@ -1215,6 +1234,7 @@ Loop:
 		case ev := <-tcellEvents:
 			app.HandleTCellEvent(ev, gowid.IgnoreUnhandledInput)
 			inactivityTimer.Reset(inactiveDuration)
+			checkPcapCacheTimer.Reset(checkPcapCacheDuration)
 
 		case ev, ok := <-afterRenderEvents:
 			// This means app.Quit() has been called, which closes the AfterRenderEvents
diff --git a/utils.go b/utils.go
index 3b774d3..aea10a4 100644
--- a/utils.go
+++ b/utils.go
@@ -22,6 +22,7 @@ import (
 	"path/filepath"
 	"regexp"
 	"runtime"
+	"sort"
 	"strconv"
 	"strings"
 	"sync"
@@ -827,6 +828,69 @@ var _ table.ICompare = IPCompare{}
 
 //======================================================================
 
+func PrunePcapCache() error {
+	// This is a new option. Best to err on the side of caution and, if not, present
+	// assume the cache can grow indefinitely - in case users are now relying on this
+	// to keep old pcaps around. I don't want to delete any files without the user's
+	// explicit permission.
+	var diskCacheSize int64 = int64(ConfInt("main.disk-cache-size-mb", -1))
+
+	if diskCacheSize == -1 {
+		log.Infof("No pcap disk cache size set. Skipping cache pruning.")
+		return nil
+	}
+
+	// Let user use MB as the most sensible unit of disk size. Convert to
+	// bytes for comparing to file sizes.
+	diskCacheSize = diskCacheSize * 1024 * 1024
+
+	log.Infof("Pruning termshark's pcap disk cache at %s...", PcapDir())
+
+	var totalSize int64
+	var fileInfos []os.FileInfo
+	err := filepath.Walk(PcapDir(),
+		func(path string, info os.FileInfo, err error) error {
+			if err == nil {
+				totalSize += info.Size()
+				fileInfos = append(fileInfos, info)
+			}
+			return nil
+		},
+	)
+	if err != nil {
+		return err
+	}
+
+	sort.Slice(fileInfos, func(i, j int) bool {
+		return fileInfos[i].ModTime().Before(fileInfos[j].ModTime())
+	})
+
+	filesRemoved := 0
+	curCacheSize := totalSize
+	for len(fileInfos) > 0 && curCacheSize > diskCacheSize {
+		err = os.Remove(filepath.Join(PcapDir(), fileInfos[0].Name()))
+		if err != nil {
+			log.Warnf("Could not remove pcap cache file %s while pruning - %v", fileInfos[0].Name(), err)
+		} else {
+			curCacheSize = curCacheSize - fileInfos[0].Size()
+			filesRemoved++
+		}
+		fileInfos = fileInfos[1:]
+	}
+
+	if filesRemoved > 0 {
+		log.Infof("Pruning complete. Removed %d old pcaps. Cache size is now %d MB",
+			filesRemoved, curCacheSize/(1024*1024))
+	} else {
+		log.Infof("Pruning complete. No old pcaps removed. Cache size is %d MB",
+			curCacheSize/(1024*1024))
+	}
+
+	return nil
+}
+
+//======================================================================
+
 var cpuProfileRunning *abool.AtomicBool
 
 func init() {