diff --git a/Makefile.am b/Makefile.am
index 2990533927adabc02c9d870ace9ab797cfc96dd2..880428c223b140b808bd936734164b4e34a81c3d 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -53,6 +53,7 @@ test_cases = \
 	tests/exists.svtest \
 	tests/header.svtest \
 	tests/address.svtest \
+	tests/size.svtest \
 	tests/lexer.svtest \
 	tests/comparators/core.svtest \
 	tests/match-types/is.svtest \
diff --git a/tests/size.svtest b/tests/size.svtest
new file mode 100644
index 0000000000000000000000000000000000000000..f16f8fc639391b576dcd8e17e877e76da12fa38f
--- /dev/null
+++ b/tests/size.svtest
@@ -0,0 +1,29 @@
+require "vnd.dovecot.testsuite";
+
+test_set "message" text:
+From: stephan@example.org
+To: nico@frop.example.com
+Subject:         Help        
+X-A:     Text
+X-B: Text            
+X-Multiline: This is a multi-line
+ header body, which should be
+ unfolded correctly.
+
+Text
+
+.
+;
+
+test "Size :under" {
+	if not size :under 1000 {
+		test_fail "size test produced unexpected result";
+	}
+}
+
+test "Size :over" {
+	if not size :over 10 {
+		test_fail "size test produced unexpected result";
+	}
+}
+