diff --git a/modules/src/malloc/check.c b/modules/src/malloc/check.c
index 1611b0872..c77d01668 100644
--- a/modules/src/malloc/check.c
+++ b/modules/src/malloc/check.c
@@ -15,7 +15,7 @@
 private acquire_malout(), check_ml_last();
 private dump_all_mallinks(), dump_free_list(), dump_mallink(), print_loop();
 private working_on();
-private unsigned int checksum();
+private size_type checksum();
 static FILE *malout;
 
 public mallink *free_list_entry();
@@ -91,7 +91,7 @@ dump_free_list(i)	{
 	for_free_list(i, ml)	{
 		if (print_loop(ml))
 			return;
-		fprintf(malout, "%ld ", ml);
+		fprintf(malout, "%ld ", (long) ml);
 	}
 	fprintf(malout, "<\n");
 }
@@ -148,7 +148,7 @@ dump_mallink(s, ml) char *s; mallink *ml;	{
 public
 check_mallinks(s) char *s;	{
 	mallink *ml;
-	unsigned int size;
+	size_type size;
 	int i;
 	char stat;
 	
@@ -218,16 +218,16 @@ check_ml_last(s) char *s;	{
 		Error("size of ml_last == 0, at %ld", s, ml_last);
 }
 
-private unsigned int
+private size_type
 checksum(ml) mallink *ml;	{
-	unsigned int sum = 0;
+	size_type sum = 0;
 	
 	if (free_of(ml))	{
-		sum += (unsigned int)_log_prev_of(ml);
-		sum += (unsigned int)_log_next_of(ml);
+		sum += (size_type)_log_prev_of(ml);
+		sum += (size_type)_log_next_of(ml);
 	}
-	sum += (unsigned int)prev_size_of(ml);
-	sum += (unsigned int)_this_size_of(ml);
+	sum += (size_type)prev_size_of(ml);
+	sum += (size_type)_this_size_of(ml);
 	return sum;
 }
 
@@ -287,6 +287,9 @@ check_work_empty(s) char *s;	{
 
 public int
 Error(fmt, s, ml) char *fmt, *s; mallink *ml;	{
+	static int already_called = 0;
+
+	if (already_called++) return 0;
 	setbuf(stdout, (char *) 0);
 	printf("%s: ", s);
 	printf(fmt, (long)ml);
diff --git a/modules/src/malloc/impl.h b/modules/src/malloc/impl.h
index 62762397b..b0d96ef6c 100644
--- a/modules/src/malloc/impl.h
+++ b/modules/src/malloc/impl.h
@@ -28,7 +28,7 @@ ALIGNMENT must be a dividor of MIN_SIZE
 
 union _inf {
 	union _inf *ptr;
-	unsigned int ui;
+	size_type ui;
 };
 
 typedef union _inf mallink;
diff --git a/modules/src/malloc/log.c b/modules/src/malloc/log.c
index f8dee7d65..7af6e634e 100644
--- a/modules/src/malloc/log.c
+++ b/modules/src/malloc/log.c
@@ -22,7 +22,7 @@ link_free_chunk(ml)
 		chain.
 	*/
 	register mallink **mlp = &free_list[-1];
-	register unsigned int n = size_of(ml);
+	register size_type n = size_of(ml);
 	register mallink *ml1;
 
 	assert(n < (1L << LOG_MAX_SIZE));
@@ -59,7 +59,7 @@ unlink_free_chunk(ml)
 	if (!prev)	{
 		/* it is the first in the chain */
 		register mallink **mlp = &free_list[-1];
-		register unsigned int n = size_of(ml);
+		register size_type n = size_of(ml);
 
 		assert(n < (1L << LOG_MAX_SIZE));
 		do {
diff --git a/modules/src/malloc/mal.c b/modules/src/malloc/mal.c
index 568d69e88..8ffbfa18d 100644
--- a/modules/src/malloc/mal.c
+++ b/modules/src/malloc/mal.c
@@ -96,10 +96,16 @@ malloc(n)
 			SBRK((int) (align((size_type) p) - (size_type) p));
 		}
 
-		p = SBRK((int)req);
+		/* SBRK takes an int; sorry ... */
+		if ((int) req < 0) {
+			p = ILL_BREAK;
+		}
+		else {
+			p = SBRK((int)req);
+		}
 		if (p == ILL_BREAK) {
 			req = n + mallink_size();
-			p = SBRK((int)req);
+			if ((int) req >= 0) p = SBRK((int)req);
 		}
 		if (p == ILL_BREAK)	{
 			/*	Now this is bad.  The system will not give us
@@ -238,7 +244,7 @@ realloc(addr, n)
 	register unsigned int n;
 {check_mallinks("realloc entry");{
 	register mallink *ml, *ph_next;
-	register unsigned int size;
+	register size_type size;
 
 	if (addr == 0) {
 		/*	Behave like most Unix realloc's when handed a
diff --git a/modules/src/malloc/phys.h b/modules/src/malloc/phys.h
index e5dc277bd..82e5e610b 100644
--- a/modules/src/malloc/phys.h
+++ b/modules/src/malloc/phys.h
@@ -16,9 +16,9 @@ publicdata mallink *ml_last;
 #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) & ~BITS)
+#define __bits(ml)		((int)((size_type)_phys_prev_of(ml) & BITS))
+#define	__free_of(ml)		((int)((size_type)_phys_prev_of(ml) & FREE_BIT))
+#define __phys_prev_of(ml)	((mallink *)((size_type)_phys_prev_of(ml) & ~BITS))
 #define prev_size_of(ml)	((char *)(ml) - \
 				 (char *)__phys_prev_of(ml) - \
 				 mallink_size() \
@@ -49,7 +49,7 @@ public Error();
 */
 #define size_of(ml)		(_this_size_of(ml) - mallink_size())
 #define	set_phys_next(ml,e) \
-	(_this_size_of(ml) = (unsigned int)((char *)(e) - (char *)(ml)))
+	(_this_size_of(ml) = (size_type)((char *)(e) - (char *)(ml)))
 #define	phys_next_of(ml)	(mallink *) ((char *)(ml) + _this_size_of(ml))
 
 #define	set_free(ml,e) \