diff --git a/include/jemalloc/jemalloc_macros.h.in b/include/jemalloc/jemalloc_macros.h.in
index 9f356f98..129240ed 100644
--- a/include/jemalloc/jemalloc_macros.h.in
+++ b/include/jemalloc/jemalloc_macros.h.in
@@ -13,11 +13,11 @@
 
 #  define MALLOCX_LG_ALIGN(la)	((int)(la))
 #  if LG_SIZEOF_PTR == 2
-#    define MALLOCX_ALIGN(a)	((int)(ffs(a)-1))
+#    define MALLOCX_ALIGN(a)	((int)(ffs((int)(a))-1))
 #  else
 #    define MALLOCX_ALIGN(a)						\
-       ((int)(((a) < (size_t)INT_MAX) ? ffs((int)(a))-1 :		\
-       ffs((int)((a)>>32))+31))
+       ((int)(((size_t)(a) < (size_t)INT_MAX) ? ffs((int)(a))-1 :	\
+       ffs((int)(((size_t)(a))>>32))+31))
 #  endif
 #  define MALLOCX_ZERO	((int)0x40)
 /*
@@ -29,7 +29,7 @@
 /*
  * Bias arena index bits so that 0 encodes "use an automatically chosen arena".
  */
-#  define MALLOCX_ARENA(a)	((int)(((a)+1) << 20))
+#  define MALLOCX_ARENA(a)	((((int)(a))+1) << 20)
 
 #if defined(__cplusplus) && defined(JEMALLOC_USE_CXX_THROW)
 #  define JEMALLOC_CXX_THROW throw()
diff --git a/test/integration/mallocx.c b/test/integration/mallocx.c
index 42eee105..d82bf422 100644
--- a/test/integration/mallocx.c
+++ b/test/integration/mallocx.c
@@ -69,18 +69,14 @@ TEST_END
 
 TEST_BEGIN(test_oom)
 {
-	size_t hugemax, size, alignment;
-
-	hugemax = get_huge_size(get_nhuge()-1);
 
 	/*
 	 * It should be impossible to allocate two objects that each consume
 	 * more than half the virtual address space.
 	 */
 	{
-		void *p;
-
-		p = mallocx(hugemax, 0);
+		size_t hugemax = get_huge_size(get_nhuge()-1);
+		void *p = mallocx(hugemax, 0);
 		if (p != NULL) {
 			assert_ptr_null(mallocx(hugemax, 0),
 			    "Expected OOM for mallocx(size=%#zx, 0)", hugemax);
@@ -89,15 +85,16 @@ TEST_BEGIN(test_oom)
 	}
 
 #if LG_SIZEOF_PTR == 3
-	size      = ZU(0x8000000000000000);
-	alignment = ZU(0x8000000000000000);
+	assert_ptr_null(mallocx(0x8000000000000000ULL,
+	    MALLOCX_ALIGN(0x8000000000000000ULL)),
+	    "Expected OOM for mallocx()");
+	assert_ptr_null(mallocx(0x8000000000000000ULL,
+	    MALLOCX_ALIGN(0x80000000)),
+	    "Expected OOM for mallocx()");
 #else
-	size      = ZU(0x80000000);
-	alignment = ZU(0x80000000);
+	assert_ptr_null(mallocx(0x80000000UL, MALLOCX_ALIGN(0x80000000UL)),
+	    "Expected OOM for mallocx()");
 #endif
-	assert_ptr_null(mallocx(size, MALLOCX_ALIGN(alignment)),
-	    "Expected OOM for mallocx(size=%#zx, MALLOCX_ALIGN(%#zx)", size,
-	    alignment);
 }
 TEST_END