diff --git a/Source/DOH/fio.c b/Source/DOH/fio.c
index 4e91a1b51..43f6dc3cf 100644
--- a/Source/DOH/fio.c
+++ b/Source/DOH/fio.c
@@ -76,6 +76,7 @@ static DOH *encode(char *name, DOH *s) {
   Seek(s, 0, SEEK_SET);
   fn = (DOH *(*)(DOH *)) Data(handle);
   ns = (*fn) (s);
+  assert(pos != -1);
   Seek(s, pos, SEEK_SET);
   if (tmp)
     Delete(tmp);
diff --git a/Source/Preprocessor/cpp.c b/Source/Preprocessor/cpp.c
index d68658eb6..5a7634f91 100644
--- a/Source/Preprocessor/cpp.c
+++ b/Source/Preprocessor/cpp.c
@@ -583,6 +583,7 @@ static List *find_args(String *s, int ismacro, String *macro_name) {
   c = Getc(s);
   if (c != '(') {
     /* Not a macro, bail out now! */
+    assert(pos != -1);
     Seek(s, pos, SEEK_SET);
     Delete(args);
     return 0;