diff --git a/src/compat/compat.h b/src/compat/compat.h
index daf177551..60daba001 100644
--- a/src/compat/compat.h
+++ b/src/compat/compat.h
@@ -119,20 +119,25 @@ int clock_nanosleep(clockid_t clockid, int flags,
                     const struct timespec *request,
                     struct timespec *remain);
 
+__attribute__ ((nonnull (2))) __attribute__ ((malloc))
 static inline char*
-notcurses_data_path(const char* f){
-  char* datadir = notcurses_data_dir();
-  if(datadir == NULL){
-    return NULL;
+notcurses_data_path(const char* ddir, const char* f){
+  char* datadir = NULL;
+  if(ddir == NULL){
+    datadir = notcurses_data_dir();
+    if(datadir == NULL){
+      return NULL;
+    }
+    ddir = datadir;
   }
-  const size_t dlen = strlen(datadir);
+  const size_t dlen = strlen(ddir);
   // cast is for benefit of c++ callers, sigh
   char* path = (char*)malloc(dlen + 1 + strlen(f) + 1);
   if(path == NULL){
     free(datadir);
     return NULL;
   }
-  strcpy(path, datadir);
+  strcpy(path, ddir);
   free(datadir);
   path[dlen] = path_separator();
   strcpy(path + dlen + 1, f);
diff --git a/src/demo/demo.c b/src/demo/demo.c
index 99784d376..627c153f5 100644
--- a/src/demo/demo.c
+++ b/src/demo/demo.c
@@ -44,7 +44,7 @@ const demoresult* demoresult_lookup(int idx){
 }
 
 char* find_data(const char* datum){
-  return notcurses_data_path(datum);
+  return notcurses_data_path(datadir, datum);
 }
 
 float delaymultiplier = 1;
@@ -510,7 +510,6 @@ int main(int argc, char** argv){
   sigaddset(&sigmask, SIGWINCH);
   pthread_sigmask(SIG_BLOCK, &sigmask, NULL);
 #endif
-  datadir = notcurses_data_dir();
   const char* spec;
   FILE* json = NULL; // emit JSON summary to this file? (-J)
   notcurses_options nopts = {};
diff --git a/src/tetris/main.cpp b/src/tetris/main.cpp
index 4f486cf45..23896a6cc 100644
--- a/src/tetris/main.cpp
+++ b/src/tetris/main.cpp
@@ -17,8 +17,8 @@
 
 std::mutex ncmtx;
 
-const std::string BackgroundFile = notcurses_data_path("tetris-background.jpg");
-const std::string LogoFile = notcurses_data_path("notcurses.png");
+const std::string BackgroundFile = notcurses_data_path(nullptr, "tetris-background.jpg");
+const std::string LogoFile = notcurses_data_path(nullptr, "notcurses.png");
 
 using namespace std::chrono_literals;