diff --git a/src/str.cpp b/src/str.cpp
index 7050f79b..5d55bbba 100644
--- a/src/str.cpp
+++ b/src/str.cpp
@@ -310,6 +310,9 @@ bool
 str::startswith(const char *s_,
                 const char *p_) noexcept
 {
+  if((s_ == nullptr) || (p_ == nullptr))
+    return false;
+
   while(*p_)
     {
       if(*p_ != *s_)