diff --git a/keyfinder_cli.cpp b/keyfinder_cli.cpp
index 5994d6c..968092b 100644
--- a/keyfinder_cli.cpp
+++ b/keyfinder_cli.cpp
@@ -265,7 +265,7 @@ int main(int argc, char** argv)
 
     opterr = 0;
 
-    char c;
+    int c;
     while ((c = getopt_long(argc, argv, "n:h", options, nullptr)) != -1)
     {
         switch (c)