diff --git a/test/T070-insert.sh b/test/T070-insert.sh
index 7e04a23d..3dd76737 100755
--- a/test/T070-insert.sh
+++ b/test/T070-insert.sh
@@ -60,7 +60,7 @@ test_expect_equal_json "$output" "$expected"
 
 test_begin_subtest "Insert duplicate message"
 notmuch insert +duptag -unread < "$gen_msg_filename"
-output=$(notmuch search --output=files "subject:insert-subject" | wc -l)
+output=$((`notmuch search --output=files "subject:insert-subject" | wc -l`))
 test_expect_equal "$output" 2
 
 test_begin_subtest "Duplicate message does not change tags"
diff --git a/test/T580-thread-search.sh b/test/T580-thread-search.sh
index 6f7106db..512559a3 100755
--- a/test/T580-thread-search.sh
+++ b/test/T580-thread-search.sh
@@ -15,7 +15,7 @@ count=0
 success=0
 for id in $(notmuch search --output=messages '*'); do
     count=$((count +1))
-    matches=$(notmuch search --output=threads "$id" | wc -l)
+    matches=$((`notmuch search --output=threads "$id" | wc -l`))
     if [ "$matches" = 1 ]; then
 	success=$((success + 1))
     fi