diff --git a/ch01.asciidoc b/ch01.asciidoc
index bf04e2b0..a0c9ac38 100644
--- a/ch01.asciidoc
+++ b/ch01.asciidoc
@@ -123,19 +123,19 @@ This most basic form of key generation, generates what are known as _Type-0_ or
 
 [[Type0_chain]]
 .Type-0 or Non-Deterministic Keys are randomly generated as needed
-image::images/Type-0 chain.png["Key generation"]
+image::images/type0_chain.png["Key generation"]
 
 ===== Type-1 deterministic (non-random) key chains
 
 [[Type1_chain]]
 .Type-1 Deterministic Keys are generated from a phrase and index number
-image::images/Type-1 chain.png["Key generation"]
+image::images/type1_chain.png["Key generation"]
 
 ===== Type-2 chained deterministic keys
 
 [[Type2_chain]]
 .Type-2 Chained Deterministic Keys are generated from a binary seed and index number
-image::images/Type-1 chain.png["Key generation"]
+image::images/type2_chain.png["Key generation"]
 
 ===== Type-2 hierarchical deterministic keys
 
diff --git a/images/Type-0 chain.png b/images/type0_chain.png
similarity index 100%
rename from images/Type-0 chain.png
rename to images/type0_chain.png
diff --git a/images/Type-0 keygen.png b/images/type0_keygen.png
similarity index 100%
rename from images/Type-0 keygen.png
rename to images/type0_keygen.png
diff --git a/images/Type-1 chain.png b/images/type1_chain.png
similarity index 100%
rename from images/Type-1 chain.png
rename to images/type1_chain.png
diff --git a/images/Type-2 chain.png b/images/type2_chain.png
similarity index 100%
rename from images/Type-2 chain.png
rename to images/type2_chain.png