diff --git a/test/integration/mallocx.c b/test/integration/mallocx.c
index 578c229a..55e1a090 100644
--- a/test/integration/mallocx.c
+++ b/test/integration/mallocx.c
@@ -1,5 +1,9 @@
 #include "test/jemalloc_test.h"
 
+#ifdef JEMALLOC_FILL
+const char *malloc_conf = "junk:false";
+#endif
+
 static unsigned
 get_nsizes_impl(const char *cmd)
 {
diff --git a/test/integration/xallocx.c b/test/integration/xallocx.c
index 5c4998b6..ad292bb5 100644
--- a/test/integration/xallocx.c
+++ b/test/integration/xallocx.c
@@ -1,5 +1,9 @@
 #include "test/jemalloc_test.h"
 
+#ifdef JEMALLOC_FILL
+const char *malloc_conf = "junk:false";
+#endif
+
 /*
  * Use a separate arena for xallocx() extension/contraction tests so that
  * internal allocation e.g. by heap profiling can't interpose allocations where