diff --git a/CHANGELOG.md b/CHANGELOG.md
index a2e18f9..8732927 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 1.20.0 - October 13, 2023
+
+- Do not allow all 0 transit numbers in CA
+
 ## 1.19.0 - October 3, 2023
 
 - Do not allow all-0 account numbers for CA
diff --git a/data/raw/pseudo_ibans.yml b/data/raw/pseudo_ibans.yml
index e439b91..e38f133 100644
--- a/data/raw/pseudo_ibans.yml
+++ b/data/raw/pseudo_ibans.yml
@@ -20,7 +20,7 @@ CA:
     end: 12
     excl: false
   :bank_code_format: "\\d{4}"
-  :branch_code_format: "\\d{5}"
+  :branch_code_format: "0{0,4}[1-9][0-9]{0,4}"
   :account_number_format: "(?!0+\\z)\\d{7,12}"
   :national_id_length: 9
   :pseudo_iban_bank_code_length: 4
diff --git a/data/structures.yml b/data/structures.yml
index c42c74f..5878b57 100644
--- a/data/structures.yml
+++ b/data/structures.yml
@@ -1500,7 +1500,7 @@ CA:
     end: 12
     excl: false
   :bank_code_format: "\\d{4}"
-  :branch_code_format: "\\d{5}"
+  :branch_code_format: 0{0,4}[1-9][0-9]{0,4}
   :account_number_format: "(?!0+\\z)\\d{7,12}"
   :national_id_length: 9
   :pseudo_iban_bank_code_length: 4
diff --git a/lib/ibandit/version.rb b/lib/ibandit/version.rb
index 02174db..9555b16 100644
--- a/lib/ibandit/version.rb
+++ b/lib/ibandit/version.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module Ibandit
-  VERSION = "1.19.0"
+  VERSION = "1.20.0"
 end
diff --git a/spec/ibandit/iban_spec.rb b/spec/ibandit/iban_spec.rb
index 75f6659..c53fc5d 100755
--- a/spec/ibandit/iban_spec.rb
+++ b/spec/ibandit/iban_spec.rb
@@ -422,10 +422,55 @@
         {
           country_code: "CA",
           bank_code: bank_code,
-          branch_code: "00063",
+          branch_code: branch_code,
           account_number: account_number,
         }
       end
+      let(:branch_code) { "00063" }
+
+      context "and a 5 digit branch code" do
+        let(:account_number) { "0123456" }
+        let(:bank_code) { "036" }
+        let(:branch_code) { "00063" }
+
+        its(:country_code) { is_expected.to eq("CA") }
+        its(:bank_code) { is_expected.to eq("0036") }
+        its(:branch_code) { is_expected.to eq("00063") }
+        its(:account_number) { is_expected.to eq("0123456") }
+        its(:swift_bank_code) { is_expected.to eq("0036") }
+        its(:swift_branch_code) { is_expected.to eq("00063") }
+        its(:swift_account_number) { is_expected.to eq("0123456") }
+        its(:swift_national_id) { is_expected.to eq("003600063") }
+        its(:pseudo_iban) { is_expected.to eq("CAZZ003600063_____0123456") }
+
+        its(:iban) { is_expected.to be_nil }
+        its(:valid?) { is_expected.to eq(true) }
+        its(:to_s) { is_expected.to eq("") }
+      end
+
+      context "for an all zero transit number" do
+        let(:account_number) { "0123456" }
+        let(:bank_code) { "036" }
+        let(:branch_code) { "00000" }
+
+        it "is invalid and has the correct errors" do
+          expect(subject.valid?).to eq(false)
+          expect(subject.errors).
+            to eq(branch_code: "format is invalid")
+        end
+      end
+
+      context "and a 4 digit branch code" do
+        let(:account_number) { "0123456" }
+        let(:bank_code) { "036" }
+        let(:branch_code) { "0063" }
+
+        it "is invalid and has the correct errors" do
+          expect(subject.valid?).to eq(false)
+          expect(subject.errors).
+            to eq(branch_code: "is the wrong length (should be 5 characters)")
+        end
+      end
 
       context "and a 3 digit bank code" do
         let(:account_number) { "0123456" }