diff --git a/test/555-checker-regression-x86const/build b/test/555-checker-regression-x86const/build
index 92ddfc9..09dcc36 100644
--- a/test/555-checker-regression-x86const/build
+++ b/test/555-checker-regression-x86const/build
@@ -27,12 +27,14 @@
 mv classes/UnresolvedClass.class classes-ex
 
 if [ ${USE_JACK} = "true" ]; then
-  jar cf classes.jill.jar -C classes .
-  jar cf classes-ex.jill.jar -C classes-ex .
+  # Create .jack files from classes generated with javac.
+  ${JILL} classes --output classes.jack
+  ${JILL} classes-ex --output classes-ex.jack
 
-  ${JACK} --import classes.jill.jar --output-dex .
+  # Create DEX files from .jack files.
+  ${JACK} --import classes.jack --output-dex .
   zip $TEST_NAME.jar classes.dex
-  ${JACK} --import classes-ex.jill.jar --output-dex .
+  ${JACK} --import classes-ex.jack --output-dex .
   zip ${TEST_NAME}-ex.jar classes.dex
 else
   if [ ${NEED_DEX} = "true" ]; then
diff --git a/test/run-test b/test/run-test
index a7a9876..f1875d7 100755
--- a/test/run-test
+++ b/test/run-test
@@ -677,9 +677,9 @@
 # Tests named '<number>-checker-*' will also have their CFGs verified with
 # Checker when compiled with Optimizing on host.
 if [[ "$TEST_NAME" =~ ^[0-9]+-checker- ]]; then
-  # Disable optimizations where Jack may simplify statements with constants
-  # (like 'null instanceof SomeType').
-  JACK="$JACK -D jack.optimization.expression-simplifier=false"
+  # Jack does not necessarily generate the same DEX output than dx. Because these tests depend
+  # on a particular DEX output, keep building them with dx for now (b/19467889).
+  USE_JACK="false"
 
   if [ "$runtime" = "art" -a "$image_suffix" = "-optimizing" ]; then
     # Optimizing has read barrier support for certain architectures