diff --git a/abstract-machine/klib/src/printf.c b/abstract-machine/klib/src/printf.c
index 04a5757..e760c3f 100644
--- a/abstract-machine/klib/src/printf.c
+++ b/abstract-machine/klib/src/printf.c
@@ -87,7 +87,7 @@ int rvsnprintf(char* out, size_t n, const char* fmt, va_list ap) {
         n --;
     }
     *out = '\0';
-    return ret - n;
+    return ret - n + 1;
 }
 
 #endif