diff --git a/pkg/filestore/blockstore.go b/pkg/filestore/blockstore.go
index d67dea93a..1e0f8e83c 100644
--- a/pkg/filestore/blockstore.go
+++ b/pkg/filestore/blockstore.go
@@ -12,6 +12,7 @@ import (
 	"fmt"
 	"io/fs"
 	"log"
+	"math"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -42,7 +43,7 @@ const NoPartIdx = -1
 var warningCount = &atomic.Int32{}
 var flushErrorCount = &atomic.Int32{}
 
-var partDataSize int64 = DefaultPartDataSize // overridden in tests
+var partDataSize int = DefaultPartDataSize // overridden in tests
 var stopFlush = &atomic.Bool{}
 
 var WFS *FileStore = &FileStore{
@@ -67,7 +68,7 @@ type WaveFile struct {
 // for circular files this is min(Size, MaxSize)
 func (f WaveFile) DataLength() int64 {
 	if f.Opts.Circular {
-		return minInt64(f.Size, f.Opts.MaxSize)
+		return min(f.Size, f.Opts.MaxSize)
 	}
 	return f.Size
 }
@@ -122,8 +123,9 @@ func (s *FileStore) MakeFile(ctx context.Context, zoneId string, name string, me
 		return fmt.Errorf("circular file cannot be ijson")
 	}
 	if opts.Circular {
-		if opts.MaxSize%partDataSize != 0 {
-			opts.MaxSize = (opts.MaxSize/partDataSize + 1) * partDataSize
+		partDataSizeInt64 := int64(partDataSize)
+		if opts.MaxSize%partDataSizeInt64 != 0 {
+			opts.MaxSize = (opts.MaxSize/partDataSizeInt64 + 1) * partDataSizeInt64
 		}
 	}
 	if opts.IJsonBudget > 0 && !opts.IJson {
@@ -249,7 +251,7 @@ func (s *FileStore) WriteAt(ctx context.Context, zoneId string, name string, off
 		if offset > file.Size {
 			return fmt.Errorf("offset is past the end of the file")
 		}
-		partMap := file.computePartMap(offset, int64(len(data)))
+		partMap := file.computePartMap(offset, len(data))
 		incompleteParts := incompletePartsFromMap(partMap)
 		err = entry.loadDataPartsIntoCache(ctx, incompleteParts)
 		if err != nil {
@@ -266,7 +268,7 @@ func (s *FileStore) AppendData(ctx context.Context, zoneId string, name string,
 		if err != nil {
 			return err
 		}
-		partMap := entry.File.computePartMap(entry.File.Size, int64(len(data)))
+		partMap := entry.File.computePartMap(entry.File.Size, len(data))
 		incompleteParts := incompletePartsFromMap(partMap)
 		if len(incompleteParts) > 0 {
 			err = entry.loadDataPartsIntoCache(ctx, incompleteParts)
@@ -332,7 +334,7 @@ func (s *FileStore) AppendIJson(ctx context.Context, zoneId string, name string,
 		if !entry.File.Opts.IJson {
 			return fmt.Errorf("file %s:%s is not an ijson file", zoneId, name)
 		}
-		partMap := entry.File.computePartMap(entry.File.Size, int64(len(data)))
+		partMap := entry.File.computePartMap(entry.File.Size, len(data))
 		incompleteParts := incompletePartsFromMap(partMap)
 		if len(incompleteParts) > 0 {
 			err = entry.loadDataPartsIntoCache(ctx, incompleteParts)
@@ -366,7 +368,7 @@ func (s *FileStore) GetAllZoneIds(ctx context.Context) ([]string, error) {
 
 // returns (offset, data, error)
 // we return the offset because the offset may have been adjusted if the size was too big (for circular files)
-func (s *FileStore) ReadAt(ctx context.Context, zoneId string, name string, offset int64, size int64) (rtnOffset int64, rtnData []byte, rtnErr error) {
+func (s *FileStore) ReadAt(ctx context.Context, zoneId string, name string, offset int64, size int) (rtnOffset int64, rtnData []byte, rtnErr error) {
 	withLock(s, zoneId, name, func(entry *CacheEntry) error {
 		rtnOffset, rtnData, rtnErr = entry.readAt(ctx, offset, size, false)
 		return nil
@@ -422,9 +424,9 @@ func (s *FileStore) FlushCache(ctx context.Context) (stats FlushStats, rtnErr er
 ///////////////////////////////////
 
 func (f *WaveFile) partIdxAtOffset(offset int64) int {
-	partIdx := int(offset / partDataSize)
+	partIdx := int(min(offset/int64(partDataSize), math.MaxInt))
 	if f.Opts.Circular {
-		maxPart := int(f.Opts.MaxSize / partDataSize)
+		maxPart := int(min(f.Opts.MaxSize/int64(partDataSize), math.MaxInt))
 		partIdx = partIdx % maxPart
 	}
 	return partIdx
@@ -449,16 +451,17 @@ func getPartIdxsFromMap(partMap map[int]int) []int {
 }
 
 // returns a map of partIdx to amount of data to write to that part
-func (file *WaveFile) computePartMap(startOffset int64, size int64) map[int]int {
+func (file *WaveFile) computePartMap(startOffset int64, size int) map[int]int {
 	partMap := make(map[int]int)
-	endOffset := startOffset + size
-	startFileOffset := startOffset - (startOffset % partDataSize)
-	for testOffset := startFileOffset; testOffset < endOffset; testOffset += partDataSize {
+	endOffset := startOffset + int64(size)
+	partDataSizeInt64 := int64(partDataSize)
+	startFileOffset := startOffset - (startOffset % partDataSizeInt64)
+	for testOffset := startFileOffset; testOffset < endOffset; testOffset += partDataSizeInt64 {
 		partIdx := file.partIdxAtOffset(testOffset)
 		partStartOffset := testOffset
-		partEndOffset := testOffset + partDataSize
+		partEndOffset := testOffset + partDataSizeInt64
 		partWriteStartOffset := 0
-		partWriteEndOffset := int(partDataSize)
+		partWriteEndOffset := partDataSize
 		if startOffset > partStartOffset && startOffset < partEndOffset {
 			partWriteStartOffset = int(startOffset - partStartOffset)
 		}
diff --git a/pkg/filestore/blockstore_cache.go b/pkg/filestore/blockstore_cache.go
index af8632022..dbb00628d 100644
--- a/pkg/filestore/blockstore_cache.go
+++ b/pkg/filestore/blockstore_cache.go
@@ -8,6 +8,7 @@ import (
 	"context"
 	"fmt"
 	"io/fs"
+	"math"
 	"sync"
 	"time"
 )
@@ -144,7 +145,7 @@ func withLockRtn[T any](s *FileStore, zoneId string, name string, fn func(*Cache
 }
 
 func (dce *DataCacheEntry) writeToPart(offset int64, data []byte) (int64, *DataCacheEntry) {
-	leftInPart := partDataSize - offset
+	leftInPart := int64(partDataSize) - offset
 	toWrite := int64(len(data))
 	if toWrite > leftInPart {
 		toWrite = leftInPart
@@ -161,7 +162,7 @@ func (entry *CacheEntry) writeAt(offset int64, data []byte, replace bool) {
 		entry.File.Size = 0
 	}
 	if entry.File.Opts.Circular {
-		startCirFileOffset := entry.File.Size - entry.File.Opts.MaxSize
+		startCirFileOffset := entry.File.Size - int64(entry.File.Opts.MaxSize)
 		if offset+int64(len(data)) <= startCirFileOffset {
 			// write is before the start of the circular file
 			return
@@ -172,11 +173,12 @@ func (entry *CacheEntry) writeAt(offset int64, data []byte, replace bool) {
 			data = data[truncateAmt:]
 			offset += truncateAmt
 		}
-		if int64(len(data)) > entry.File.Opts.MaxSize {
+		dataLen := int64(len(data))
+		if dataLen > entry.File.Opts.MaxSize {
 			// truncate data (from the front), update offset
-			truncateAmt := int64(len(data)) - entry.File.Opts.MaxSize
+			truncateAmt := int(max(dataLen-entry.File.Opts.MaxSize, 0))
 			data = data[truncateAmt:]
-			offset += truncateAmt
+			offset += int64(truncateAmt)
 		}
 	}
 	endWriteOffset := offset + int64(len(data))
@@ -184,14 +186,19 @@ func (entry *CacheEntry) writeAt(offset int64, data []byte, replace bool) {
 		entry.DataEntries = make(map[int]*DataCacheEntry)
 	}
 	for len(data) > 0 {
-		partIdx := int(offset / partDataSize)
+		partIdxI64 := offset / int64(partDataSize)
+		if partIdxI64 > math.MaxInt {
+			// too big
+			return
+		}
+		partIdx := int(partIdxI64)
 		if entry.File.Opts.Circular {
-			maxPart := int(entry.File.Opts.MaxSize / partDataSize)
+			maxPart := int(min(entry.File.Opts.MaxSize/int64(partDataSize), math.MaxInt))
 			partIdx = partIdx % maxPart
 		}
-		partOffset := offset % partDataSize
+		partOffset := int(offset % int64(partDataSize))
 		partData := entry.getOrCreateDataCacheEntry(partIdx)
-		nw, newDce := partData.writeToPart(partOffset, data)
+		nw, newDce := partData.writeToPart(int64(partOffset), data)
 		entry.DataEntries[partIdx] = newDce
 		data = data[nw:]
 		offset += nw
@@ -203,7 +210,7 @@ func (entry *CacheEntry) writeAt(offset int64, data []byte, replace bool) {
 }
 
 // returns (realOffset, data, error)
-func (entry *CacheEntry) readAt(ctx context.Context, offset int64, size int64, readFull bool) (int64, []byte, error) {
+func (entry *CacheEntry) readAt(ctx context.Context, offset int64, size int, readFull bool) (int64, []byte, error) {
 	if offset < 0 {
 		return 0, nil, fmt.Errorf("offset cannot be negative")
 	}
@@ -212,20 +219,20 @@ func (entry *CacheEntry) readAt(ctx context.Context, offset int64, size int64, r
 		return 0, nil, err
 	}
 	if readFull {
-		size = file.Size - offset
+		size = int(min(file.Size-offset, math.MaxInt))
 	}
-	if offset+size > file.Size {
-		size = file.Size - offset
+	if offset+int64(size) > file.Size {
+		size = int(min(file.Size-offset, math.MaxInt))
 	}
 	if file.Opts.Circular {
 		realDataOffset := int64(0)
-		if file.Size > file.Opts.MaxSize {
-			realDataOffset = file.Size - file.Opts.MaxSize
+		if file.Size > int64(file.Opts.MaxSize) {
+			realDataOffset = file.Size - int64(file.Opts.MaxSize)
 		}
 		if offset < realDataOffset {
 			truncateAmt := realDataOffset - offset
 			offset += truncateAmt
-			size -= truncateAmt
+			size = int(max(int64(size)-truncateAmt, 0))
 		}
 		if size <= 0 {
 			return realDataOffset, nil, nil
@@ -250,11 +257,11 @@ func (entry *CacheEntry) readAt(ctx context.Context, offset int64, size int64, r
 		} else {
 			partData = partDataEntry.Data[0:partDataSize]
 		}
-		partOffset := curReadOffset % partDataSize
-		amtToRead := minInt64(partDataSize-partOffset, amtLeftToRead)
+		partOffset := int(curReadOffset % int64(partDataSize))
+		amtToRead := min(partDataSize-partOffset, amtLeftToRead)
 		rtnData = append(rtnData, partData[partOffset:partOffset+amtToRead]...)
 		amtLeftToRead -= amtToRead
-		curReadOffset += amtToRead
+		curReadOffset += int64(amtToRead)
 	}
 	return offset, rtnData, nil
 }
diff --git a/pkg/filestore/blockstore_test.go b/pkg/filestore/blockstore_test.go
index 42fc7a343..2cda20647 100644
--- a/pkg/filestore/blockstore_test.go
+++ b/pkg/filestore/blockstore_test.go
@@ -306,7 +306,7 @@ func checkFileByteCount(t *testing.T, ctx context.Context, zoneId string, name s
 }
 
 func checkFileDataAt(t *testing.T, ctx context.Context, zoneId string, name string, offset int64, data string) {
-	_, rdata, err := WFS.ReadAt(ctx, zoneId, name, offset, int64(len(data)))
+	_, rdata, err := WFS.ReadAt(ctx, zoneId, name, offset, len(data))
 	if err != nil {
 		t.Errorf("error reading data for file %q: %v", name, err)
 		return
diff --git a/pkg/remote/fileshare/wavefs/wavefs.go b/pkg/remote/fileshare/wavefs/wavefs.go
index 1aaca37a1..5382d7bbf 100644
--- a/pkg/remote/fileshare/wavefs/wavefs.go
+++ b/pkg/remote/fileshare/wavefs/wavefs.go
@@ -69,7 +69,7 @@ func (c WaveClient) Read(ctx context.Context, conn *connparse.Connection, data w
 		return nil, fmt.Errorf("error cleaning path: %w", err)
 	}
 	if data.At != nil {
-		_, dataBuf, err := filestore.WFS.ReadAt(ctx, zoneId, fileName, data.At.Offset, int64(data.At.Size))
+		_, dataBuf, err := filestore.WFS.ReadAt(ctx, zoneId, fileName, data.At.Offset, data.At.Size)
 		if err == nil {
 			return &wshrpc.FileData{Info: data.Info, Data64: base64.StdEncoding.EncodeToString(dataBuf)}, nil
 		} else if errors.Is(err, fs.ErrNotExist) {