diff --git a/src/Brofiler.cc b/src/Brofiler.cc
index 783d027761..ce16916635 100644
--- a/src/Brofiler.cc
+++ b/src/Brofiler.cc
@@ -1,4 +1,5 @@
 #include <cstdio>
+#include <cstring>
 #include <utility>
 #include <algorithm>
 #include "Brofiler.h"
@@ -48,7 +49,38 @@ bool Brofiler::WriteStats()
 	char* bf = getenv("BRO_PROFILER_FILE");
 	if ( ! bf ) return false;
 
-	FILE* f = fopen(bf, "w");
+	bool gen_unique = false;
+	const char* p = strstr(bf, ".X");
+	if ( p )
+		{
+		gen_unique = true;
+		while ( *(++p) )
+			{
+			if ( *p != 'X' )
+				{
+				gen_unique = false;
+				break;
+				}
+			}
+		}
+
+	FILE* f;
+
+	if ( gen_unique )
+		{
+		int fd = mkstemp(bf);
+		if ( fd == -1 )
+			{
+			reporter->Error("Failed to generate unique file name from BRO_PROFILER_FILE: %s\n", bf);
+			return false;
+			}
+		f = fdopen(fd, "w");
+		}
+	else
+		{
+		f = fopen(bf, "w");
+		}
+
 	if ( ! f )
 		{
 		reporter->Error("Failed to open BRO_PROFILER_FILE destination '%s' for writing\n", bf);
diff --git a/src/Brofiler.h b/src/Brofiler.h
index edbe1e932c..698a2e03a6 100644
--- a/src/Brofiler.h
+++ b/src/Brofiler.h
@@ -26,7 +26,9 @@ public:
 	/**
 	 * Combines usage stats from current run with any read from ReadStats(),
 	 * then writes information to file pointed to by environment variable
-	 * BRO_PROFILER_FILE.
+	 * BRO_PROFILER_FILE.  If the value of that env. variable ends with
+	 * ".XXXX" (any amount of X's), then it is first passed through mkstemp
+	 * to get a unique file.
 	 *
 	 * @return: true when usage info is written, otherwise false.
 	 */
diff --git a/testing/Makefile b/testing/Makefile
index f65d5a1fef..1c82580ec4 100644
--- a/testing/Makefile
+++ b/testing/Makefile
@@ -12,6 +12,7 @@ make-brief:
 	@for repo in $(DIRS); do (cd $$repo && make brief ); done
 
 coverage:
+	@for repo in $(DIRS); do (cd $$repo && echo "Coverage for '$$repo' dir:" && make coverage); done
 	@test -f btest/coverage.log && cp btest/coverage.log `mktemp brocov.tmp.XXX` || true
 	@for f in external/*/coverage.log; do test -f $$f && cp $$f `mktemp brocov.tmp.XXX` || true; done
 	@echo "Complete test suite code coverage:"
diff --git a/testing/btest/Makefile b/testing/btest/Makefile
index a2ca30609a..caf0a786f7 100644
--- a/testing/btest/Makefile
+++ b/testing/btest/Makefile
@@ -2,16 +2,23 @@
 DIAG=diag.log
 BTEST=../../aux/btest/btest
 
-all: cleanup
-    # Showing all tests.
-	@$(BTEST) -f $(DIAG)
-	@../scripts/coverage-calc ".tmp/script-coverage*" coverage.log `pwd`/../../scripts
+all: cleanup btest-verbose coverage
 
-brief: cleanup
-    # Brief output showing only failed tests.
+# Showing all tests.
+btest-verbose:
+	@$(BTEST) -f $(DIAG)
+
+brief: cleanup btest-brief coverage
+
+# Brief output showing only failed tests.
+btest-brief:
 	@$(BTEST) -b -f $(DIAG)
+
+coverage:
 	@../scripts/coverage-calc ".tmp/script-coverage*" coverage.log `pwd`/../../scripts
 
 cleanup:
 	@rm -f $(DIAG)
 	@rm -f .tmp/script-coverage*
+
+.PHONY: all btest-verbose brief btest-brief coverage cleanup
diff --git a/testing/btest/btest.cfg b/testing/btest/btest.cfg
index 2126e733e7..8c36ef6c1a 100644
--- a/testing/btest/btest.cfg
+++ b/testing/btest/btest.cfg
@@ -18,4 +18,4 @@ DIST=%(testbase)s/../..
 BUILD=%(testbase)s/../../build
 TEST_DIFF_CANONIFIER=$SCRIPTS/diff-canonifier
 TMPDIR=%(testbase)s/.tmp
-BRO_PROFILER_FILE=%(testbase)s/.tmp/script-coverage
+BRO_PROFILER_FILE=%(testbase)s/.tmp/script-coverage.XXXX
diff --git a/testing/external/Makefile b/testing/external/Makefile
index 994d8962c0..b705734003 100644
--- a/testing/external/Makefile
+++ b/testing/external/Makefile
@@ -24,3 +24,7 @@ push:
 status:
 	@for repo in $(REPOS); do ( cd $$repo && echo '>>' $$repo && git status -bs && echo ); done
 
+coverage:
+	@for repo in $(REPOS); do (cd $$repo && echo "Coverage for '$$repo' repo:" && make coverage); done
+
+.PHONY: all brief init pull push status coverage
diff --git a/testing/external/subdir-btest.cfg b/testing/external/subdir-btest.cfg
index 7b1d59cb07..b9ddf309b4 100644
--- a/testing/external/subdir-btest.cfg
+++ b/testing/external/subdir-btest.cfg
@@ -17,4 +17,4 @@ TRACES=%(testbase)s/Traces
 SCRIPTS=%(testbase)s/../scripts
 DIST=%(testbase)s/../../..
 BUILD=%(testbase)s/../../../build
-BRO_PROFILER_FILE=%(testbase)s/.tmp/script-coverage
+BRO_PROFILER_FILE=%(testbase)s/.tmp/script-coverage.XXXX
diff --git a/testing/scripts/btest-bg-run b/testing/scripts/btest-bg-run
deleted file mode 100755
index 64a38b9759..0000000000
--- a/testing/scripts/btest-bg-run
+++ /dev/null
@@ -1,7 +0,0 @@
-#! /usr/bin/env bash
-
-# This is a wrapper script to btest's real btest-bg-run.  It's used
-# when collecting Bro script coverage statistics so that two independent
-# Bro processing don't try to write those usage statistics to the same file.
-
-BRO_PROFILER_FILE=`mktemp $TMPDIR/script-coverage.XXXX` $BTEST_PATH/btest-bg-run $@