diff --git a/server/src/error.ts b/server/src/error.ts
deleted file mode 100644
index 2f661f9..0000000
--- a/server/src/error.ts
+++ /dev/null
@@ -1,5 +0,0 @@
-import CMakeListener from './parser/CMakeListener';
-
-export default class CMakeErrorListener extends CMakeListener {
-
-}
\ No newline at end of file
diff --git a/server/src/semanticDiagnostics.ts b/server/src/semanticDiagnostics.ts
new file mode 100644
index 0000000..ccb0ff8
--- /dev/null
+++ b/server/src/semanticDiagnostics.ts
@@ -0,0 +1,118 @@
+import { Diagnostic, DiagnosticSeverity } from "vscode-languageserver";
+import Token from "./parser/antlr4/Token";
+import CMakeListener from "./parser/CMakeListener";
+
+export default class SemanticDiagnosticsListener extends CMakeListener {
+    private diagnostics: Diagnostic[] = [];
+
+    enterAddSubDirCmd(ctx: any): void {
+        this.checkCmdCase(ctx.start);
+    }
+
+    enterBreakCmd(ctx: any): void {
+        this.checkCmdCase(ctx.start);
+    }
+
+    enterContinueCmd(ctx: any): void {
+        this.checkCmdCase(ctx.start);
+    }
+
+    enterElseCmd(ctx: any): void {
+        this.checkCmdCase(ctx.start);
+    }
+
+    enterElseIfCmd(ctx: any): void {
+        this.checkCmdCase(ctx.start);
+    }
+
+    enterEndForeachCmd(ctx: any): void {
+        this.checkCmdCase(ctx.start);
+    }
+
+    enterEndFunctionCmd(ctx: any): void {
+        this.checkCmdCase(ctx.start);
+    }
+
+    enterEndIfCmd(ctx: any): void {
+        this.checkCmdCase(ctx.start);
+    }
+
+    enterEndMacroCmd(ctx: any): void {
+        this.checkCmdCase(ctx.start);
+    }
+
+    enterEndWhileCmd(ctx: any): void {
+        this.checkCmdCase(ctx.start);
+    }
+
+    enterForeachCmd(ctx: any): void {
+        this.checkCmdCase(ctx.start);
+    }
+
+    enterFunctionCmd(ctx: any): void {
+        this.checkCmdCase(ctx.start);
+    }
+
+    enterIfCmd(ctx: any): void {
+        this.checkCmdCase(ctx.start);
+    }
+
+    enterIncludeCmd(ctx: any): void {
+        this.checkCmdCase(ctx.start);
+    }
+
+    enterMacroCmd(ctx: any): void {
+        this.checkCmdCase(ctx.start);
+    }
+
+    enterOptionCmd(ctx: any): void {
+        this.checkCmdCase(ctx.start);
+    }
+
+    enterWhileCmd(ctx: any): void {
+        this.checkCmdCase(ctx.start);
+    }
+
+    enterSetCmd(ctx: any): void {
+        this.checkCmdCase(ctx.start);
+    }
+
+    enterOtherCmd(ctx: any): void {
+        this.checkCmdCase(ctx.start);
+    }
+
+    checkCmdCase(token: Token) {
+        const text: string = token.text;
+        const line: number = token.line, column: number = token.column;
+        const isLowerCase = ((cmdText: string) => {
+            for (const ch of cmdText) {
+                if (ch.toLowerCase() !== ch) {
+                    return false;
+                }
+            }
+            return true;
+        })(text);
+
+        if (!isLowerCase) {
+            this.diagnostics.push({
+                range: {
+                    start: {
+                        line: line - 1,
+                        character: column
+                    },
+                    end: {
+                        line: line - 1,
+                        character: column + text.length
+                    }
+                },
+                severity: DiagnosticSeverity.Information,
+                source: 'cmake-intellisence',
+                message: "cmake encourage lower case command name"
+            });
+        }
+    }
+
+    getSemanticDiagnostics(): Diagnostic[] {
+        return this.diagnostics;
+    }
+}
\ No newline at end of file
diff --git a/server/src/server.ts b/server/src/server.ts
index b45b68b..ba3c349 100644
--- a/server/src/server.ts
+++ b/server/src/server.ts
@@ -19,7 +19,7 @@ import { existsSync } from 'fs';
 import { URI, Utils } from 'vscode-uri';
 import * as builtinCmds from './builtin-cmds.json';
 import { cmakeInfo } from './cmakeInfo';
-import CMakeErrorListener from './diagnostics';
+import SyntaxErrorListener from './syntaxDiagnostics';
 import { SymbolListener } from './docSymbols';
 import { FormatListener } from './format';
 import antlr4 from './parser/antlr4/index.js';
@@ -30,6 +30,7 @@ import { extSettings } from './settings';
 import { DefinationListener, incToBaseDir, refToDef, topScope } from './symbolTable/goToDefination';
 import { getFileContext } from './utils';
 import { createLogger } from './logging';
+import SemanticDiagnosticsListener from './semanticDiagnostics';
 
 type Word = {
     text: string,
@@ -392,14 +393,17 @@ documents.onDidChangeContent((change: TextDocumentChangeEvent<TextDocument>) =>
     const tokenStream = new antlr4.CommonTokenStream(lexer);
     const parser = new CMakeParser(tokenStream);
     parser.removeErrorListeners();
-    const errorListener = new CMakeErrorListener();
-    parser.addErrorListener(errorListener);
+    const syntaxErrorListener = new SyntaxErrorListener();
+    parser.addErrorListener(syntaxErrorListener);
     const tree = parser.file();
-    const symbolListener = new SymbolListener();
-    antlr4.tree.ParseTreeWalker.DEFAULT.walk(symbolListener, tree);
+    const semanticListener = new SemanticDiagnosticsListener();
+    antlr4.tree.ParseTreeWalker.DEFAULT.walk(semanticListener, tree);
     connection.sendDiagnostics({
         uri: change.document.uri,
-        diagnostics: errorListener.getDiagnostics()
+        diagnostics: [
+            ...syntaxErrorListener.getSyntaxErrors(),
+            ...semanticListener.getSemanticDiagnostics()
+        ]
     });
 });
 
diff --git a/server/src/diagnostics.ts b/server/src/syntaxDiagnostics.ts
similarity index 72%
rename from server/src/diagnostics.ts
rename to server/src/syntaxDiagnostics.ts
index 15c6218..c9dcb69 100644
--- a/server/src/diagnostics.ts
+++ b/server/src/syntaxDiagnostics.ts
@@ -1,7 +1,7 @@
-import { Diagnostic } from 'vscode-languageserver';
+import { Diagnostic, DiagnosticSeverity } from 'vscode-languageserver';
 import ErrorListener from './parser/antlr4/error/ErrorListener';
 
-export default class CMakeErrorListener extends ErrorListener {
+export default class SyntaxErrorListener extends ErrorListener {
     private diagnostics: Diagnostic[] = [];
 
     /**
@@ -25,15 +25,17 @@ export default class CMakeErrorListener extends ErrorListener {
                     character: column + offendingSymbol.text.length
                 }
             },
+            severity: DiagnosticSeverity.Error,
+            source: 'cmake-intellisence',
             message: msg
         });
     }
 
-    public getDiagnostics(): Diagnostic[] {
+    public getSyntaxErrors(): Diagnostic[] {
         return this.diagnostics;
     }
 
-    public clearDiagnostics() {
+    public clearSyntaxErrors() {
         this.diagnostics = [];
     }
 }
\ No newline at end of file