1 files changed, 10 insertions, 0 deletions
diff --git a/main.go b/main.go
index 1968fb2..27bdf87 100644
--- a/main.go
+++ b/main.go
@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"regexp"
 	"strings"
 )
 
@@ -52,6 +53,15 @@ func firstPass(
 			parts := strings.Split(line, ":")
 			for _, label := range parts[:len(parts)-1] {
 				label = strings.TrimSpace(strings.ToUpper(label))
+				isCharsetAllowed := regexp.MustCompile(`^[a-zA-Z0-9_-]*$`).MatchString(label)
+				if !isCharsetAllowed {
+					return nil, fmt.Errorf(
+						"File %s, line %d:\nLabel \"%s\" contains special characters. Only alphanumeric, dashes and underscores are allowed",
+						input_file_name,
+						line_nb+1,
+						label,
+					)
+				}
 				if _, ok := state.Labels[label]; ok {
 					return nil, fmt.Errorf(
 						"File %s, line %d:\nLabel %s is already defined",