diff --git a/utils/buildit/GNUmakefile b/utils/buildit/GNUmakefile
index 997188333c1..585d4856ffa 100644
--- a/utils/buildit/GNUmakefile
+++ b/utils/buildit/GNUmakefile
@@ -34,8 +34,8 @@ DSTROOT = $(OBJROOT)/../dst
 
 PREFIX = /usr/local
 
-# Unless assertions are forced on in the GMAKE command line, disable them.
-ifdef ENABLE_ASSERTIONS
+# Unless assertions are forced on in the GMAKE command line, enable them.
+ifndef ENABLE_ASSERTIONS
 LLVM_ASSERTIONS := yes
 else
 LLVM_ASSERTIONS := no