diff --git a/compress/decompress.go b/compress/decompress.go
index d21ec482c..80773b34c 100644
--- a/compress/decompress.go
+++ b/compress/decompress.go
@@ -195,6 +195,9 @@ func NewDecompressor(compressedFile string) (*Decompressor, error) {
 
 	for i < dictSize {
 		d, ns := binary.Uvarint(data[i:])
+		if d > 2048 {
+			return nil, fmt.Errorf("dictionary is invalid: patternMaxDepth=%d", d)
+		}
 		depths = append(depths, d)
 		if d > patternMaxDepth {
 			patternMaxDepth = d
@@ -232,6 +235,9 @@ func NewDecompressor(compressedFile string) (*Decompressor, error) {
 	i = 0
 	for i < dictSize {
 		d, ns := binary.Uvarint(data[i:])
+		if d > 2048 {
+			return nil, fmt.Errorf("dictionary is invalid: posMaxDepth=%d", d)
+		}
 		posDepths = append(posDepths, d)
 		if d > posMaxDepth {
 			posMaxDepth = d
@@ -241,6 +247,9 @@ func NewDecompressor(compressedFile string) (*Decompressor, error) {
 		i += uint64(n)
 		poss = append(poss, pos)
 	}
+	if posMaxDepth > 31 {
+		fmt.Printf("alex: %d\n", posMaxDepth)
+	}
 
 	if dictSize > 0 {
 		var bitLen int