diff --git a/Base/Configurations/Debug.xcconfig b/Base/Configurations/Debug.xcconfig
index cc0eae1..6ef0040 100644
--- a/Base/Configurations/Debug.xcconfig
+++ b/Base/Configurations/Debug.xcconfig
@@ -27,6 +27,11 @@ ONLY_ACTIVE_ARCH = YES
 // These settings catch some errors in integer arithmetic
 OTHER_CFLAGS = -ftrapv
 
+// Other flags to pass to the Swift compiler
+//
+// This enables conditional compilation with #if DEBUG
+OTHER_SWIFT_FLAGS = -D DEBUG
+
 // Whether to strip debugging symbols when copying the built product to its
 // final installation location
 STRIP_INSTALLED_PRODUCT = NO