diff --git a/memory-constraints.macros b/memory-constraints.macros
index 2851de0..046ddd7 100644
--- a/memory-constraints.macros
+++ b/memory-constraints.macros
@@ -5,10 +5,10 @@
 # rather than just giving you OOM
 #
 
-# m: memory limit in Bs per core; default is 1000000
+# m: memory limit in MBs per core; default is 1000
 %limit_build(m:) \
     _threads="`/usr/bin/getconf _NPROCESSORS_ONLN`" \
-    _core_memory="%{-m:%{-m*}}%{!-m:1000000}" \
+    _core_memory="%{-m:%{-m*}}%{!-m:1000}" \
     echo "Available memory:" \
     cat /proc/meminfo \
     echo "System limits:" \
@@ -17,7 +17,7 @@
     if test "$_threads" -gt 1 ; then \
         mem_per_process="$_core_memory" \
         max_mem=$(awk '/MemTotal/ { print $2 }' /proc/meminfo) \
-        max_jobs="$(($max_mem / $mem_per_process))" \
+        max_jobs="$(($max_mem / ($mem_per_process * 1000)))" \
         test "$_threads" -gt "$max_jobs" && $_threads="$max_jobs" && echo "Warning: Reducing number of jobs to $max_jobs because of memory limits" \
         test "$_threads" -le 0 && $_threads=1 && echo "Warning: Do not use the parallel build at all becuse of memory limits" \
     fi \
diff --git a/memory-constraints.spec b/memory-constraints.spec
index 5638594..42b78c2 100644
--- a/memory-constraints.spec
+++ b/memory-constraints.spec
@@ -26,6 +26,7 @@ URL:            https://www.opensuse.org/
 Source0:        %{name}.macros
 BuildRequires:  rpm
 Requires:       awk
+Requires:       coreutils
 BuildArch:      noarch
 
 %description