diff --git a/libcpp/ChangeLog b/libcpp/ChangeLog
index df8da71f329..1c314ea112d 100644
--- a/libcpp/ChangeLog
+++ b/libcpp/ChangeLog
@@ -1,5 +1,8 @@
 2019-05-07  Nathan Sidwell  <nathan@acm.org>
 
+	* files.c (_cpp_stack_file): Empty filenames aren't dependencies.
+	* mkdeps.c (deps_add_dep): Assert not empty.
+
 	* include/mkdeps.h (deps_write): Add PHONY arg.
 	(deps_phony_targets): Delete.
 	* init.c (cpp_finish): Just call deps_write.
diff --git a/libcpp/files.c b/libcpp/files.c
index b0ac22be6ba..3255cbfb6c8 100644
--- a/libcpp/files.c
+++ b/libcpp/files.c
@@ -906,11 +906,11 @@ _cpp_stack_file (cpp_reader *pfile, _cpp_file *file, bool import,
     sysp = MAX (pfile->buffer->sysp,  file->dir->sysp);
 
   /* Add the file to the dependencies on its first inclusion.  */
-  if (CPP_OPTION (pfile, deps.style) > !!sysp && !file->stack_count)
-    {
-      if (!file->main_file || !CPP_OPTION (pfile, deps.ignore_main_file))
-	deps_add_dep (pfile->deps, file->path);
-    }
+  if (!file->stack_count
+      && CPP_OPTION (pfile, deps.style) > !!sysp
+      && file->path[0]
+      && (!file->main_file || !CPP_OPTION (pfile, deps.ignore_main_file)))
+    deps_add_dep (pfile->deps, file->path);
 
   /* Clear buffer_valid since _cpp_clean_line messes it up.  */
   file->buffer_valid = false;
diff --git a/libcpp/mkdeps.c b/libcpp/mkdeps.c
index a9a050cf110..96cc49b9cc1 100644
--- a/libcpp/mkdeps.c
+++ b/libcpp/mkdeps.c
@@ -281,6 +281,8 @@ deps_add_default_target (struct mkdeps *d, const char *tgt)
 void
 deps_add_dep (struct mkdeps *d, const char *t)
 {
+  gcc_assert (*t);
+
   t = apply_vpath (d, t);
 
   d->deps.push (xstrdup (t));