diff --git a/scripts/base/protocols/smtp/entities.bro b/scripts/base/protocols/smtp/entities.bro
index e2bb40b7aa..e3c89ff36c 100644
--- a/scripts/base/protocols/smtp/entities.bro
+++ b/scripts/base/protocols/smtp/entities.bro
@@ -69,6 +69,11 @@ export {
 	## The on-disk prefix for files to be extracted from MIME entity bodies.
 	const extraction_prefix = "smtp-entity" &redef;
 
+	## If set, never generate MD5s. This is mainly for testing purposes to create
+	## reproducable output in the case that the decision whether to create
+	## checksums depends on environment specifics.
+	const never_calc_md5 = F &redef;
+
 	global log_mime: event(rec: EntityInfo);
 }
 
@@ -121,7 +126,7 @@ event mime_segment_data(c: connection, length: count, data: string) &priority=-5
 
 	if ( c$smtp$current_entity$content_len == 0 )
 		{
-		if ( generate_md5 in c$smtp$current_entity$mime_type )
+		if ( generate_md5 in c$smtp$current_entity$mime_type && ! never_calc_md5 )
 			c$smtp$current_entity$calc_md5 = T;
 
 		if ( c$smtp$current_entity$calc_md5 )
diff --git a/testing/external/scripts/skel/test.skeleton b/testing/external/scripts/skel/test.skeleton
index e0291d70df..becd970d78 100644
--- a/testing/external/scripts/skel/test.skeleton
+++ b/testing/external/scripts/skel/test.skeleton
@@ -1,2 +1,6 @@
-@TEST-EXEC: zcat $TRACES/test.trace.gz | bro -r - test-all-policy
-@TEST-EXEC: $SCRIPTS/diff-all *.log
+# @TEST-EXEC: zcat $TRACES/trace.gz | bro -r - %INPUT
+# @TEST-EXEC: $SCRIPTS/diff-all *.log
+
+@load testing-setup
+@load test-all-policy
+
diff --git a/testing/external/scripts/testing-setup.bro b/testing/external/scripts/testing-setup.bro
new file mode 100644
index 0000000000..fa5664a877
--- /dev/null
+++ b/testing/external/scripts/testing-setup.bro
@@ -0,0 +1,6 @@
+# Sets some testing specific options.
+
+@ifdef ( SMTP::never_calc_md5 )
+        # MDD5s can depend on libmagic output.
+	redef SMTP::never_calc_md5 = T;
+@endif
diff --git a/testing/external/subdir-btest.cfg b/testing/external/subdir-btest.cfg
index f780f7f90a..dd9a57c879 100644
--- a/testing/external/subdir-btest.cfg
+++ b/testing/external/subdir-btest.cfg
@@ -6,7 +6,7 @@ IgnoreDirs  = .svn CVS .tmp
 IgnoreFiles = *.tmp *.swp #* *.trace .gitignore *.skeleton
 
 [environment]
-BROPATH=`bash -c %(testbase)s/../../../build/bro-path-dev`
+BROPATH=`bash -c %(testbase)s/../../../build/bro-path-dev`:%(testbase)s/../scripts
 BRO_SEED_FILE=%(testbase)s/../random.seed
 TZ=UTC
 LC_ALL=C