diff --git a/org.eclipse.jgit/resources/org/eclipse/jgit/internal/JGitText.properties b/org.eclipse.jgit/resources/org/eclipse/jgit/internal/JGitText.properties
index 8ecc5fd69..c535bf50f 100644
--- a/org.eclipse.jgit/resources/org/eclipse/jgit/internal/JGitText.properties
+++ b/org.eclipse.jgit/resources/org/eclipse/jgit/internal/JGitText.properties
@@ -509,7 +509,7 @@ openingConnection=Opening connection
 operationCanceled=Operation {0} was canceled
 outputHasAlreadyBeenStarted=Output has already been started.
 overflowedReftableBlock=Overflowed reftable block
-packChecksumMismatch=Pack checksum mismatch detected for pack file {0}
+packChecksumMismatch=Pack checksum mismatch detected for pack file {0}: .pack has {1} whilst .idx has {2}
 packCorruptedWhileWritingToFilesystem=Pack corrupted while writing to filesystem
 packDoesNotMatchIndex=Pack {0} does not match index
 packedRefsHandleIsStale=packed-refs handle is stale, {0}. retry
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackFile.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackFile.java
index 71f64ae11..e85d85cbd 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackFile.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackFile.java
@@ -187,7 +187,8 @@ public class PackFile implements Iterable<PackIndex.MutableEntry> {
 				} else if (!Arrays.equals(packChecksum, idx.packChecksum)) {
 					throw new PackMismatchException(MessageFormat.format(
 							JGitText.get().packChecksumMismatch,
-							packFile.getPath()));
+							packFile.getPath(), packChecksum,
+							idx.packChecksum));
 				}
 				loadedIdx = idx;
 			} catch (InterruptedIOException e) {
@@ -753,10 +754,10 @@ public class PackFile implements Iterable<PackIndex.MutableEntry> {
 		fd.readFully(buf, 0, 20);
 		if (!Arrays.equals(buf, packChecksum)) {
 			throw new PackMismatchException(MessageFormat.format(
-					JGitText.get().packObjectCountMismatch
-					, ObjectId.fromRaw(buf).name()
-					, ObjectId.fromRaw(idx.packChecksum).name()
-					, getPackFile()));
+					JGitText.get().packChecksumMismatch,
+					getPackFile(),
+					ObjectId.fromRaw(buf).name(),
+					ObjectId.fromRaw(idx.packChecksum).name()));
 		}
 	}