diff --git a/tests/suites/test_suite_pkcs7.function b/tests/suites/test_suite_pkcs7.function
index 9dce25e..91fe47b 100644
--- a/tests/suites/test_suite_pkcs7.function
+++ b/tests/suites/test_suite_pkcs7.function
@@ -125,8 +125,8 @@
     TEST_ASSERT(file != NULL);
 
     datalen = st.st_size;
-    /* Add 1 so that data is non-NULL for zero length input */
-    ASSERT_ALLOC(data, datalen + 1);
+    /* Special-case for zero-length input so that data will be non-NULL */
+    ASSERT_ALLOC(data, datalen == 0 ? 1 : datalen);
     buflen = fread((void *) data, sizeof(unsigned char), datalen, file);
     TEST_EQUAL(buflen, datalen);