diff --git a/sqlcipher.xcodeproj/project.pbxproj b/sqlcipher.xcodeproj/project.pbxproj
index 5cd6c3e..a5d9a3a 100644
--- a/sqlcipher.xcodeproj/project.pbxproj
+++ b/sqlcipher.xcodeproj/project.pbxproj
@@ -199,6 +199,7 @@
 					"-DSQLITE_HAS_CODEC",
 					"-DNDEBUG",
 					"-DSQLITE_TEMP_STORE=2",
+					"-DSQLITE_THREADSAFE",
 				);
 				OTHER_LDFLAGS = "";
 				PRODUCT_NAME = sqlcipher;
@@ -222,6 +223,7 @@
 					"-DNDEBUG",
 					"-DSQLITE_OS_UNIX=1",
 					"-DSQLITE_TEMP_STORE=2",
+					"-DSQLITE_THREADSAFE",
 				);
 				OTHER_LDFLAGS = "";
 				PRODUCT_NAME = sqlcipher;