1 files changed, 1 insertions, 0 deletions
diff --git a/src/istring.h b/src/istring.h
index 6f5bfce93..3a66465d0 100644
--- a/src/istring.h
+++ b/src/istring.h
@@ -39,6 +39,7 @@ struct IString {
 
   IString() : str(nullptr) {}
   IString(const char *s, bool reuse=true) { // if reuse=true, then input is assumed to remain alive; not copied
+    assert(s);
     set(s, reuse);
   }