diff --git a/spec/git-version-spec.cr b/spec/git-version-spec.cr
index 444e222..bdffbc7 100644
--- a/spec/git-version-spec.cr
+++ b/spec/git-version-spec.cr
@@ -204,6 +204,41 @@ describe GitVersion do
     end
   end
 
+  it "identifier can be specified in uppercase" do
+    tmp = InTmp.new
+
+    begin
+      git = GitVersion::Git.new("dev", "master", "feature:", "BREAKING CHANGE:", tmp.@tmpdir)
+
+      tmp.exec %(git init)
+      tmp.exec %(git checkout -b master)
+      tmp.exec %(git commit --no-gpg-sign --allow-empty -m "1")
+      tmp.exec %(git tag "1.0.0")
+
+      tmp.exec %(git checkout -b my-fancy.branch)
+      tmp.exec %(git commit --no-gpg-sign --allow-empty -m "2")
+
+      tmp.exec %(git commit --no-gpg-sign --allow-empty -m "feature: blah
+
+BREAKING CHANGE: XYZ")
+
+      tmp.exec %(git checkout master)
+
+      version = git.get_new_version
+
+      # no new commit in master, expect no version bump
+      version.should eq("1.0.0")
+
+      tmp.exec %(git merge my-fancy.branch)
+
+      version = git.get_new_version
+
+      version.should eq("2.0.0")
+    ensure
+      tmp.cleanup
+    end
+  end
+
   it "correct version on feature after second commit" do
     tmp = InTmp.new
 
@@ -954,7 +989,6 @@ it "get previous version - first commit" do
     tmp.exec %(git checkout -b master)
     tmp.exec %(git commit --no-gpg-sign --allow-empty -m "1")
 
-
     # git-version should accept the breaking tag on commit with dir2
     version = git.get_previous_version
     version.should eq("0.0.0")
diff --git a/src/git-version.cr b/src/git-version.cr
index a21e1e7..40ebc8f 100644
--- a/src/git-version.cr
+++ b/src/git-version.cr
@@ -14,6 +14,9 @@ module GitVersion
     def initialize(@dev_branch : String, @release_branch : String, @minor_identifier : String, @major_identifier : String,
                    @folder = FileUtils.pwd, @prefix : String = "", @log_paths : String = "", @suffix : String = "",
                    @skip_prerelease : Bool = false)
+      @major_identifier = @major_identifier.downcase
+      @minor_identifier = @minor_identifier.downcase
+
       @major_id_is_regex = false
       @minor_id_is_regex = false
       if match = /\/(.*)\//.match(@major_identifier)