diff --git a/public/libbacktrace/backtrace.hpp b/public/libbacktrace/backtrace.hpp
index d95c4025..159b68bd 100644
--- a/public/libbacktrace/backtrace.hpp
+++ b/public/libbacktrace/backtrace.hpp
@@ -94,7 +94,10 @@ extern struct backtrace_state *backtrace_create_state (
    data to be loaded directly from the file with base_address=0.
    The caller is responsible for converting runtime virtual addresses
    to ELF virtual addresses before passing them to backtrace_pcinfo
-   or backtrace_syminfo.  */
+   or backtrace_syminfo.
+   The filename is copied into state-owned memory (the file is opened
+   lazily on first use), so the caller's buffer need not outlive this
+   call.  */
 
 extern struct backtrace_state *backtrace_create_state_for_file (
     const char *filename, int threaded,
diff --git a/public/libbacktrace/state.cpp b/public/libbacktrace/state.cpp
index e7d6160f..af620577 100644
--- a/public/libbacktrace/state.cpp
+++ b/public/libbacktrace/state.cpp
@@ -81,11 +81,20 @@ backtrace_create_state_for_file (const char *filename, int threaded,
 				 backtrace_error_callback error_callback,
 				 void *data)
 {
-  struct backtrace_state *state;
+  /* The state opens the file lazily on first use (fileline_initialize),
+     so it must own the filename: the caller's buffer may be freed as
+     soon as this returns.  */
+  const size_t len = strlen (filename) + 1;
+  char *copy = (char*)backtrace_alloc (NULL, len, error_callback, data);
+  if (copy == NULL)
+    return NULL;
+  memcpy (copy, filename, len);
 
-  state = backtrace_create_state (filename, threaded, error_callback, data);
-  if (state != NULL)
-    state->external_file = 1;
+  struct backtrace_state *state =
+    backtrace_create_state (copy, threaded, error_callback, data);
+  if (state == NULL)
+    return NULL;
+  state->external_file = 1;
 
   return state;
 }