diff --git a/memory-constraints.macros b/memory-constraints.macros
index 5f6ec13..7450b88 100644
--- a/memory-constraints.macros
+++ b/memory-constraints.macros
@@ -5,10 +5,10 @@
 # rather than just giving you OOM
 #
 
-# m: memory limit in MBs per core; default is 1000
+# m: memory limit in Bs per core; default is 1000000
 %limit_build(m:) \
     _threads="`/usr/bin/getconf _NPROCESSORS_ONLN`"
-    _core_memory="%{-m:%{-m*}}%{!-m:1000}"
+    _core_memory="%{-m:%{-m*}}%{!-m:1000000}"
     echo "Available memory:" \
     cat /proc/meminfo \
     echo "System limits:" \