diff --git a/handlers/aliases/analyzer/analyzer.go b/handlers/aliases/analyzer/analyzer.go
index 98cd418..2f399d1 100644
--- a/handlers/aliases/analyzer/analyzer.go
+++ b/handlers/aliases/analyzer/analyzer.go
@@ -1,13 +1,33 @@
 package analyzer
 
 import (
-	"config-lsp/handlers/hosts"
+	"config-lsp/common"
+	"config-lsp/handlers/aliases"
+	"config-lsp/utils"
 
 	protocol "github.com/tliron/glsp/protocol_3_16"
 )
 
 func Analyze(
-	d *hosts.HostsDocument,
+	d *aliases.AliasesDocument,
 ) []protocol.Diagnostic {
-	return nil
+	errors := analyzeValuesAreValid(*d.Parser)
+
+	if len(errors) > 0 {
+		return utils.Map(
+			errors,
+			func(err common.LSPError) protocol.Diagnostic {
+				return err.ToDiagnostic()
+			},
+		)
+	}
+
+	errors = append(errors, analyzeDoubleKeys(d)...)
+
+	return utils.Map(
+		errors,
+		func(err common.LSPError) protocol.Diagnostic {
+			return err.ToDiagnostic()
+		},
+	)
 }
diff --git a/handlers/aliases/analyzer/double_keys.go b/handlers/aliases/analyzer/double_keys.go
new file mode 100644
index 0000000..68afeb5
--- /dev/null
+++ b/handlers/aliases/analyzer/double_keys.go
@@ -0,0 +1,21 @@
+package analyzer
+
+import (
+	"config-lsp/common"
+	"config-lsp/handlers/aliases"
+	"config-lsp/handlers/aliases/indexes"
+)
+
+func analyzeDoubleKeys(
+	d *aliases.AliasesDocument,
+) []common.LSPError {
+	indexes, errors := indexes.CreateIndexes(*d.Parser)
+
+	d.Indexes = &indexes
+
+	if len(errors) > 0 {
+		return errors
+	}
+
+	return nil
+}
diff --git a/handlers/aliases/analyzer/double_keys_test.go b/handlers/aliases/analyzer/double_keys_test.go
new file mode 100644
index 0000000..c0e9214
--- /dev/null
+++ b/handlers/aliases/analyzer/double_keys_test.go
@@ -0,0 +1,73 @@
+package analyzer
+
+import (
+	"config-lsp/handlers/aliases"
+	"config-lsp/handlers/aliases/ast"
+	"config-lsp/utils"
+	"testing"
+)
+
+func TestWorks(
+	t *testing.T,
+) {
+	input := utils.Dedent(`
+support: michael
+marketing: john
+support: jane
+`)
+	p := ast.NewAliasesParser()
+	errors := p.Parse(input)
+
+	d := aliases.AliasesDocument{
+		Parser: &p,
+	}
+
+	if len(errors) != 0 {
+		t.Errorf("Expected no errors, got %v", errors)
+	}
+
+	errors = analyzeDoubleKeys(&d)
+
+	if !(len(errors) == 1) {
+		t.Errorf("Expected 1 error, got %v", errors)
+	}
+
+	if d.Indexes == nil {
+		t.Errorf("Expected indexes to be set")
+	}
+}
+
+func TestValidWorks(
+	t *testing.T,
+) {
+	input := utils.Dedent(`
+support: michael
+marketing: john
+supportgroup: jane
+suppor: jane
+`)
+	p := ast.NewAliasesParser()
+	errors := p.Parse(input)
+
+	d := aliases.AliasesDocument{
+		Parser: &p,
+	}
+
+	if len(errors) != 0 {
+		t.Errorf("Expected no errors, got %v", errors)
+	}
+
+	errors = analyzeDoubleKeys(&d)
+
+	if !(len(errors) == 0) {
+		t.Errorf("Expected 0 errors, got %v", errors)
+	}
+
+	if d.Indexes == nil {
+		t.Errorf("Expected indexes to be set")
+	}
+
+	if d.Indexes.Keys["support"] == nil {
+		t.Errorf("Expected support to be in indexes")
+	}
+}
diff --git a/handlers/aliases/shared.go b/handlers/aliases/shared.go
index 86ef6be..b47d360 100644
--- a/handlers/aliases/shared.go
+++ b/handlers/aliases/shared.go
@@ -7,9 +7,9 @@ import (
 	protocol "github.com/tliron/glsp/protocol_3_16"
 )
 
-type HostsDocument struct {
+type AliasesDocument struct {
 	Parser  *ast.AliasesParser
 	Indexes *indexes.AliasesIndexes
 }
 
-var DocumentParserMap = map[protocol.DocumentUri]*HostsDocument{}
+var DocumentParserMap = map[protocol.DocumentUri]*AliasesDocument{}