diff --git a/book/source/08-signature_internals.md b/book/source/08-signature_internals.md
index f9f2234..0e3bc53 100644
--- a/book/source/08-signature_internals.md
+++ b/book/source/08-signature_internals.md
@@ -10,4 +10,4 @@
 
 ## Notations
 
-## Zooming in: Package structure
+## Zooming in: Packet structure
diff --git a/book/source/10-encryption.md b/book/source/10-encryption.md
index bec0d55..ca48db6 100644
--- a/book/source/10-encryption.md
+++ b/book/source/10-encryption.md
@@ -30,7 +30,7 @@ Core concept:
 
 ### Implications of how a recipient cert is "addressed" (fingerprint/key-ID vs. user-ID) (preferences, expiration, revocation)
 
-## Zooming in: Package structure and internals
+## Zooming in: Packet structure
 
 ### Encryption yields a 'wrapped' openpgp packet stream
 
diff --git a/book/source/12-compression.md b/book/source/12-compression.md
index 8cc6808..aa6e6d4 100644
--- a/book/source/12-compression.md
+++ b/book/source/12-compression.md
@@ -1,5 +1,5 @@
 # Compression
 
-## Zooming in: Package structure and internals
+## Zooming in: Packet structure
 
 ### Decompression yields a 'wrapped' openpgp packet stream