diff --git a/test/blackbox-tests/dune.inc b/test/blackbox-tests/dune.inc
index b6d9aa5110eb..993efd5e108b 100644
--- a/test/blackbox-tests/dune.inc
+++ b/test/blackbox-tests/dune.inc
@@ -555,6 +555,14 @@
    test-cases/github1856
    (progn (run %{exe:cram.exe} -test run.t) (diff? run.t run.t.corrected)))))
 
+(alias
+ (name github1946)
+ (deps (package dune) (source_tree test-cases/github1946))
+ (action
+  (chdir
+   test-cases/github1946
+   (progn (run %{exe:cram.exe} -test run.t) (diff? run.t run.t.corrected)))))
+
 (alias
  (name github20)
  (deps (package dune) (source_tree test-cases/github20))
@@ -1383,6 +1391,7 @@
   (alias github1616)
   (alias github1811)
   (alias github1856)
+  (alias github1946)
   (alias github20)
   (alias github24)
   (alias github25)
@@ -1540,6 +1549,7 @@
   (alias github1616)
   (alias github1811)
   (alias github1856)
+  (alias github1946)
   (alias github20)
   (alias github24)
   (alias github25)
diff --git a/test/blackbox-tests/test-cases/github1946/dune b/test/blackbox-tests/test-cases/github1946/dune
new file mode 100644
index 000000000000..77b87f88ab83
--- /dev/null
+++ b/test/blackbox-tests/test-cases/github1946/dune
@@ -0,0 +1,13 @@
+(library
+ (name usesppx1)
+ (modules ())
+ (preprocess (pps ppx1)))
+
+(library
+ (name usesppx2)
+ (modules ())
+ (preprocess (pps ppx2)))
+
+(alias
+ (name default)
+ (action (echo %{read:.merlin})))
diff --git a/test/blackbox-tests/test-cases/github1946/dune-project b/test/blackbox-tests/test-cases/github1946/dune-project
new file mode 100644
index 000000000000..bc63500b73c0
--- /dev/null
+++ b/test/blackbox-tests/test-cases/github1946/dune-project
@@ -0,0 +1 @@
+(lang dune 1.8)
\ No newline at end of file
diff --git a/test/blackbox-tests/test-cases/github1946/ppx1/dune b/test/blackbox-tests/test-cases/github1946/ppx1/dune
new file mode 100644
index 000000000000..354bdddf0d6c
--- /dev/null
+++ b/test/blackbox-tests/test-cases/github1946/ppx1/dune
@@ -0,0 +1,3 @@
+(library
+ (name ppx1)
+ (kind ppx_rewriter))
diff --git a/test/blackbox-tests/test-cases/github1946/ppx2/dune b/test/blackbox-tests/test-cases/github1946/ppx2/dune
new file mode 100644
index 000000000000..c908ec42a6af
--- /dev/null
+++ b/test/blackbox-tests/test-cases/github1946/ppx2/dune
@@ -0,0 +1,3 @@
+(library
+ (name ppx2)
+ (kind ppx_rewriter))
diff --git a/test/blackbox-tests/test-cases/github1946/run.t b/test/blackbox-tests/test-cases/github1946/run.t
new file mode 100644
index 000000000000..6a18e6deefcf
--- /dev/null
+++ b/test/blackbox-tests/test-cases/github1946/run.t
@@ -0,0 +1,2 @@
+  $ dune build --display short --profile release | grep "FLG -ppx"
+  [1]