diff --git a/deltachat-ffi/build.rs b/deltachat-ffi/build.rs
index a4273dfbf..247f3dae7 100644
--- a/deltachat-ffi/build.rs
+++ b/deltachat-ffi/build.rs
@@ -22,9 +22,9 @@ fn main() {
         url = env::var("CARGO_PKG_HOMEPAGE").unwrap_or_else(|_| "".to_string()),
         version = env::var("CARGO_PKG_VERSION").unwrap(),
         libs_priv = libs_priv,
-        prefix = env::var("PREFIX").unwrap(),
-        libdir = env::var("LIBDIR").unwrap(),
-        includedir = env::var("INCLUDEDIR").unwrap(),
+        prefix = env::var("PREFIX").unwrap_or_else(|_| "/usr/local".to_string()),
+        libdir = env::var("LIBDIR").unwrap_or_else(|_| "/usr/local/lib".to_string()),
+        includedir = env::var("INCLUDEDIR").unwrap_or_else(|_| "/usr/local/include".to_string()),
     );
 
     fs::create_dir_all(target_path.join("pkgconfig")).unwrap();