diff --git a/modules/src/malloc/impl.h b/modules/src/malloc/impl.h
index 3b92fe8b2..5e88e9bbf 100644
--- a/modules/src/malloc/impl.h
+++ b/modules/src/malloc/impl.h
@@ -9,9 +9,8 @@
 
 #define	MIN_SIZE	(1<<LOG_MIN_SIZE)
 #define	MAX_FLIST	(LOG_MAX_SIZE - LOG_MIN_SIZE)
-#if ALIGNMENT != 1 && ALIGNMENT != 2 && ALIGNMENT != 4 && ALIGNMENT != 8 &&\
-    ALIGNMENT != 16
-ALIGNMENT must be a (small) power of two !!!
+#if ALIGNMENT != 4 && ALIGNMENT != 8 && ALIGNMENT != 16
+ALIGNMENT must be 4, 8, or 16
 #endif
 #define align(n)	(((n) + (ALIGNMENT - 1)) & ~(ALIGNMENT - 1))
 
diff --git a/modules/src/malloc/log.h b/modules/src/malloc/log.h
index a15c7b523..d4b651758 100644
--- a/modules/src/malloc/log.h
+++ b/modules/src/malloc/log.h
@@ -11,18 +11,14 @@ public link_free_chunk(), unlink_free_chunk();
 public mallink *first_present(), *search_free_list();
 
 #ifdef STORE
-#define in_store(ml)		((size_type)_log_prev_of(ml) & 01)
+#define in_store(ml)		((size_type)_phys_prev_of(ml) & STORE_BIT)
 #define set_store(ml, e) \
-	(_log_prev_of(ml) = (mallink *) \
-		((e) ? (size_type) _log_prev_of(ml) | 01 : \
-		       (size_type) _log_prev_of(ml) & ~01))
-#define log_prev_of(ml)		(mallink *)((size_type)_log_prev_of(ml) & ~01)
-#define set_log_prev(ml,e) \
-	(_log_prev_of(ml) = (mallink *)((char *)e + in_store(ml)))
-#else
+	(_phys_prev_of(ml) = (mallink *) \
+		((e) ? (size_type) _phys_prev_of(ml) | STORE_BIT : \
+		       (size_type) _phys_prev_of(ml) & ~STORE_BIT))
+#endif
 #define	set_log_prev(ml,e)	(_log_prev_of(ml) = (e))
 #define	log_prev_of(ml)		(mallink *) (_log_prev_of(ml))
-#endif
 
 #define	set_log_next(ml,e)	(_log_next_of(ml) = (e))
 #define	log_next_of(ml)		(mallink *) (_log_next_of(ml))
diff --git a/modules/src/malloc/mal.c b/modules/src/malloc/mal.c
index 5c1606609..c1c51e63a 100644
--- a/modules/src/malloc/mal.c
+++ b/modules/src/malloc/mal.c
@@ -96,6 +96,7 @@ malloc(n)
 		}
 
 		p = SBRK((int)req);
+		assert((size_type)p == align((size_type)p));
 		if (p == ILL_BREAK) {
 			req = n + mallink_size();
 			p = SBRK((int)req);
diff --git a/modules/src/malloc/phys.h b/modules/src/malloc/phys.h
index 79bb0952c..aa05c975e 100644
--- a/modules/src/malloc/phys.h
+++ b/modules/src/malloc/phys.h
@@ -8,8 +8,17 @@
 */
 publicdata mallink *ml_last;
 
-#define	__free_of(ml)		((size_type)_phys_prev_of(ml) & 01)
-#define __phys_prev_of(ml)	(mallink *)((size_type)_phys_prev_of(ml) & ~01)
+#define FREE_BIT		01
+#ifdef STORE
+#define STORE_BIT		02
+#define BITS			(FREE_BIT|STORE_BIT)
+#else
+#define BITS			(FREE_BIT)
+#endif
+
+#define __bits(ml)		((size_type)_phys_prev_of(ml) & BITS)
+#define	__free_of(ml)		((size_type)_phys_prev_of(ml) & FREE_BIT)
+#define __phys_prev_of(ml)	(mallink *)((size_type)_phys_prev_of(ml) & ~FREE_BIT)
 #define prev_size_of(ml)	((char *)(ml) - \
 				 (char *)__phys_prev_of(ml) - \
 				 mallink_size() \
@@ -45,8 +54,8 @@ public Error();
 
 #define	set_free(ml,e) \
 	(_phys_prev_of(ml) = (mallink *) \
-		((e) ? (size_type) _phys_prev_of(ml) | 01 : \
-		       (size_type) _phys_prev_of(ml) & ~01))
+		((e) ? (size_type) _phys_prev_of(ml) | FREE_BIT : \
+		       (size_type) _phys_prev_of(ml) & ~FREE_BIT))
 #define	free_of(ml)		(__free_of(ml))
 
 #define coalesce_forw(ml,nxt)	( unlink_free_chunk(nxt), \