diff --git a/libsqlite3-sys/build.rs b/libsqlite3-sys/build.rs
index 14c5f2a..c4cd5aa 100644
--- a/libsqlite3-sys/build.rs
+++ b/libsqlite3-sys/build.rs
@@ -127,6 +127,19 @@ mod build_bundled {
         }
         println!("cargo:rerun-if-env-changed=SQLITE_MAX_EXPR_DEPTH");
 
+        if let Ok(extras) = env::var("LIBSQLITE3_FLAGS") {
+            for extra in extras.split_whitespace() {
+                if extra.starts_with("-D") || extra.starts_with("-U") {
+                    cfg.flag(extra);
+                } else if extra.starts_with("SQLITE_") {
+                    cfg.flag(&format!("-D{}", extra));
+                } else {
+                    panic!("Don't understand {} in LIBSQLITE3_FLAGS", extra);
+                }
+            }
+        }
+        println!("cargo:rerun-if-env-changed=LIBSQLITE3_FLAGS");
+
         cfg.compile("libsqlite3.a");
 
         println!("cargo:lib_dir={}", out_dir);