diff --git a/HashProgramOutput.sh b/HashProgramOutput.sh
--- a/HashProgramOutput.sh
+++ b/HashProgramOutput.sh
@@ -9,10 +9,16 @@
 is_md5sum=1
 if [ ! -x "$md5cmd" ]; then
     md5cmd=$(which md5)
-    is_md5sum=0
-    if [ ! -x "$md5cmd" ]; then
-        echo "error: unable to find either 'md5sum' or 'md5'"
-        exit 1
+    if [ -x "$md5cmd" ]; then
+        is_md5sum=0
+    else
+        md5cmd=$(which csum)
+        if [ ! -x "$md5cmd" ]; then
+            echo "error: unable to find either 'md5sum', 'md5' or 'csum'"
+            exit 1
+        fi
+        # Pass options to make csum behave identically to md5sum.
+        md5cmd="${md5cmd} -h MD5 -"
     fi
 fi