diff --git a/common/iomux.c b/common/iomux.c
index b9088aa3b5..c428f7110a 100644
--- a/common/iomux.c
+++ b/common/iomux.c
@@ -158,8 +158,12 @@ int iomux_replace_device(const int console, const char *old, const char *new)
 			return -ENOMEM;
 		}
 
-		strcat(tmp, ",");
-		strcat(tmp, name);
+		if (arg) {
+			strcat(tmp, ",");
+			strcat(tmp, name);
+		}
+		else
+			strcpy(tmp, name);
 
 		arg = tmp;
 		size = strlen(tmp) + 1;