diff --git a/test/961-default-iface-resolution-gen/build b/test/961-default-iface-resolution-gen/build
index f2c2225..d719a9f 100755
--- a/test/961-default-iface-resolution-gen/build
+++ b/test/961-default-iface-resolution-gen/build
@@ -23,4 +23,4 @@
 ./util-src/generate_java.py ./src ./expected.txt
 
 # dx runs out of memory with default 256M, give it more memory.
-./default-build "$@" --experimental default-methods --dx-vm-option -JXmx512M
+./default-build "$@" --experimental default-methods --dx-vm-option -JXmx1024M
diff --git a/test/964-default-iface-init-gen/build b/test/964-default-iface-init-gen/build
index a800151..e504690 100755
--- a/test/964-default-iface-init-gen/build
+++ b/test/964-default-iface-init-gen/build
@@ -23,4 +23,4 @@
 ./util-src/generate_java.py ./src ./expected.txt
 
 # dx runs out of memory with just 256m, so increase it.
-./default-build "$@" --experimental default-methods --dx-vm-option -JXmx512M
+./default-build "$@" --experimental default-methods --dx-vm-option -JXmx1024M