diff --git a/ctl/inspect.go b/ctl/inspect.go
index 09de20370..55a3eaf35 100644
--- a/ctl/inspect.go
+++ b/ctl/inspect.go
@@ -29,6 +29,7 @@ import (
 	"syscall"
 	"text/tabwriter"
 	"time"
+	"unsafe"
 
 	"github.com/gogo/protobuf/proto"
 	"github.com/pilosa/pilosa/v2"
@@ -360,16 +361,24 @@ func (cmd *InspectCommand) InspectFile(f *os.File, fi os.FileInfo) error {
 			fmt.Fprintf(cmd.Stderr, "inspect command: munmap failed: %v", err)
 		}
 	}()
+	mappedFrom := uintptr(unsafe.Pointer(&data[0]))
+	mappedTo := mappedFrom + uintptr(len(data))
 	// Attach the mmap file to the bitmap.
 	t := time.Now()
 	fmt.Fprintf(cmd.Stderr, "inspecting bitmap...")
 	var info roaring.BitmapInfo
-	_, _, err = roaring.InspectBinary(data, true, &info)
+	bitmap, _, err := roaring.InspectBinary(data, true, &info)
 	fmt.Fprintf(cmd.Stderr, " (%s)\n", time.Since(t))
 	cmd.DisplayInfo(info)
 	if err != nil {
 		return errors.Wrap(err, "inspecting")
 	}
+	mappedIn, mappedOut, unmappedIn, errs, err := bitmap.SanityCheckMapping(mappedFrom, mappedTo)
+	if err != nil {
+		fmt.Fprintf(cmd.Stderr, "sanity check: %d mapped in, %d mapped out, %d unmapped in, %d errors\n",
+			mappedIn, mappedOut, unmappedIn, errs)
+		fmt.Fprintf(cmd.Stderr, "last error: %v\n", err)
+	}
 	return nil
 }
 
diff --git a/roaring/roaring.go b/roaring/roaring.go
index d5ec88712..5f7c8e97b 100644
--- a/roaring/roaring.go
+++ b/roaring/roaring.go
@@ -5957,7 +5957,7 @@ func (op *op) UnmarshalBinary(data []byte) error {
 
 	switch op.typ {
 	case opTypeAdd, opTypeRemove:
-		// nothing to do, just being not-default
+		op.opN = 1
 	case opTypeAddBatch, opTypeRemoveBatch:
 		// This ensures that in doing 13+op.value*8, the max int won't be exceeded and a wrap around case
 		// (resulting in a negative value) won't occur in the slice indexing while writing
@@ -5968,8 +5968,9 @@ func (op *op) UnmarshalBinary(data []byte) error {
 			return fmt.Errorf("op data truncated - expected %d, got %d", 13+op.value*8, len(data))
 		}
 		_, _ = h.Write(data[13 : 13+op.value*8])
-		op.values = make([]uint64, op.value)
-		for i := uint64(0); i < op.value; i++ {
+		op.opN = int(op.value)
+		op.values = make([]uint64, op.opN)
+		for i := range op.values {
 			start := 13 + i*8
 			op.values[i] = binary.LittleEndian.Uint64(data[start : start+8])
 		}
diff --git a/roaring/unmarshal_binary.go b/roaring/unmarshal_binary.go
index 72d73e961..a29bba516 100644
--- a/roaring/unmarshal_binary.go
+++ b/roaring/unmarshal_binary.go
@@ -58,7 +58,10 @@ func (b *Bitmap) UnmarshalBinary(data []byte) (err error) {
 		default:
 			panic("invalid container type")
 		}
-		newC.setMapped(true)
+		// If we're using the iterator's pointer, we're "mapped". But
+		// for instance, small arrays may use their own data structures,
+		// which is fine.
+		newC.setMapped(newC.pointer == itrPointer)
 		if !b.preferMapping {
 			newC = newC.unmapOrClone()
 		}
@@ -150,10 +153,14 @@ func InspectBinary(data []byte, mapped bool, info *BitmapInfo) (b *Bitmap, mappe
 		default:
 			panic("invalid container type")
 		}
-		newC.setMapped(true)
+		// If our pointer isn't itrPointer, we aren't actually mapped.
+		newC.setMapped(newC.pointer == itrPointer)
 		if !mapped {
 			newC = newC.unmapOrClone()
 		}
+		// Pristine means this is the original object read in from
+		// roaring data, even if it's not mapped, which this is for
+		// now.
 		newC.flags |= flagPristine
 		if newC.flags&flagMapped != 0 {
 			mappedAny = true
@@ -169,6 +176,7 @@ func InspectBinary(data []byte, mapped bool, info *BitmapInfo) (b *Bitmap, mappe
 		})
 		info.ContainerCount++
 		info.BitCount += uint64(newC.n)
+		b.Containers.Put(itrKey, newC)
 		itrKey, itrCType, itrN, itrLen, itrPointer, itrErr = itr.Next()
 	}
 	// note: if we get a non-EOF err, it's possible that we made SOME