diff --git a/README.md b/README.md
index fbb4129..4e85292 100644
--- a/README.md
+++ b/README.md
@@ -5,7 +5,7 @@ It has colorful syntax highlighting and integrate with [ccc](https://github.com/
 
 # Usage
 ```sh
-vip -c file # Cat mode
+vip -c file # Cat(1) mode with syntax highlighting
 vip file
 ```
 
diff --git a/config.h b/config.h
index d2f3090..51304d6 100644
--- a/config.h
+++ b/config.h
@@ -119,7 +119,7 @@ language_t langs[] = {
 		"//",
 		"/*",
 		"*/",
-		{ "const", "switch", "if", "while", "for", "break", "continue", "return", "else", "struct", "union", "typedef", "static", "enum", "case", "sizeof", "#include", "#define", "#if", "#elseif", "#endif", "int|", "long|", "double|", "float|", "char|", "unsigned|", "void|", "size_t|", "uint8_t|", NULL },
+		{ "const", "default", "switch", "if", "while", "for", "break", "continue", "return", "else", "struct", "union", "typedef", "static", "enum", "case", "sizeof", "#include", "#define", "#if", "#elseif", "#endif", "int|", "short|", "long|", "double|", "float|", "char|", "unsigned|", "void|", "size_t|", "uint8_t|", NULL },
 		{ ".c", ".h", ".cpp", NULL },
 	},
 };
diff --git a/vip.c b/vip.c
index a815c3f..27fc35f 100644
--- a/vip.c
+++ b/vip.c
@@ -782,12 +782,22 @@ int is_symbol(int c)
 }
 
 void update_highlight(row_t *row)
-{
+{	
 	row->hl = realloc(row->hl, row->render_size);
 	memset(row->hl, NORMAL, row->render_size);
 
 	if (cur_editor->syntax == NULL) return;
 
+	if (strcmp(cur_editor->syntax->filetype, "c")) return;
+	// diff
+	// --- YELLOW
+	// +++ PEACH
+	// @@ OVERLAY0
+	// index TEAL
+	// diff BLUE
+	// + GREEN
+	// - RED
+
 	char **keywords = cur_editor->syntax->keywords;
 
 	char *scs = cur_editor->syntax->singleline_comment_start;