diff --git a/tools/dlc3.c b/tools/dlc3.c
index 07f0f21..d94eb36 100644
--- a/tools/dlc3.c
+++ b/tools/dlc3.c
@@ -94,7 +94,7 @@ static struct parameters parse_args(int argc, char *argv[])
                 error(EINVAL, "Option %s", arg);
 
             char opt = arg[1];
-            const char *optarg;
+            const char *optarg = NULL;
 
             switch (opt) {
                 case 'b': case 'r':
diff --git a/tools/elc3.c b/tools/elc3.c
index fd8a05b..0e85075 100644
--- a/tools/elc3.c
+++ b/tools/elc3.c
@@ -88,7 +88,7 @@ static struct parameters parse_args(int argc, char *argv[])
                 error(EINVAL, "Option %s", arg);
 
             char opt = arg[1];
-            const char *optarg;
+            const char *optarg = NULL;
 
             switch (opt) {
                 case 'b': case 'm': case 'r':