diff --git a/src/lib/malloc/malloc.go b/src/lib/malloc/malloc.go
index 8e4397a0b14..fec53f08fd0 100644
--- a/src/lib/malloc/malloc.go
+++ b/src/lib/malloc/malloc.go
@@ -17,7 +17,7 @@ type Stats struct {
 	EnableGC	bool;
 }
 
-func Alloc(uint64) *byte
+func Alloc(uintptr) *byte
 func Free(*byte)
 func GetStats() *Stats
 func Lookup(*byte) (*byte, uintptr)
diff --git a/src/runtime/mgc0.c b/src/runtime/mgc0.c
index 71f5fc98078..d58d6ce44d1 100644
--- a/src/runtime/mgc0.c
+++ b/src/runtime/mgc0.c
@@ -212,7 +212,7 @@ gc(int32 force)
 		else
 			gcpercent = atoi(p);
 	}
-	if(gcpercent < 0 || sizeof(void*) == 4)	// TODO(rsc): broken on 32-bit right now
+	if(gcpercent < 0)
 		return;
 
 	semacquire(&gcsema);
diff --git a/test/mallocrand.go b/test/mallocrand.go
index b933f6be450..59da01d44c5 100644
--- a/test/mallocrand.go
+++ b/test/mallocrand.go
@@ -39,13 +39,13 @@ func prime() {
 		b := malloc.Alloc(1<<uint(i));
 		malloc.Free(b);
 	}
-	for i := uint64(0); i < 256; i++ {
+	for i := uintptr(0); i < 256; i++ {
 		b := malloc.Alloc(i<<12);
 		malloc.Free(b);
 	}
 }
 
-func memset(b *byte, c byte, n uint64) {
+func memset(b *byte, c byte, n uintptr) {
 	np := uintptr(n);
 	for i := uintptr(0); i < np; i++ {
 		*(*byte)(unsafe.Pointer(uintptr(unsafe.Pointer(b))+i)) = c;
@@ -55,7 +55,7 @@ func memset(b *byte, c byte, n uint64) {
 func main() {
 	flag.Parse();
 //	prime();
-	var blocks [1] struct { base *byte; siz uint64; };
+	var blocks [1] struct { base *byte; siz uintptr; };
 	for i := 0; i < 1<<12; i++ {
 		if i%(1<<10) == 0 && *chatty {
 			println(i);
@@ -65,19 +65,19 @@ func main() {
 		//	println("Free", blocks[b].siz, blocks[b].base);
 			malloc.Free(blocks[b].base);
 			blocks[b].base = nil;
-			allocated -= blocks[b].siz;
+			allocated -= uint64(blocks[b].siz);
 			continue
 		}
-		siz := uint64(rand.Int() >> (11 + rand.Uint32() % 20));
+		siz := uintptr(rand.Int() >> (11 + rand.Uint32() % 20));
 		base := malloc.Alloc(siz);
-	//	ptr := uint64(syscall.BytePtr(base))+uint64(siz/2);
+	//	ptr := uintptr(syscall.BytePtr(base))+uintptr(siz/2);
 	//	obj, size, ref, ok := allocator.find(ptr);
 	//	if obj != base || *ref != 0 || !ok {
 	//		panicln("find", siz, obj, ref, ok);
 	//	}
 		blocks[b].base = base;
 		blocks[b].siz = siz;
-		allocated += siz;
+		allocated += uint64(siz);
 	//	println("Alloc", siz, base);
 		memset(base, 0xbb, siz);
 		bigger();
diff --git a/test/mallocrep.go b/test/mallocrep.go
index 6aa8fdf8cbd..6306e59ebc0 100644
--- a/test/mallocrep.go
+++ b/test/mallocrep.go
@@ -36,11 +36,14 @@ func main() {
 			if i == 0 && *chatty {
 				println("First alloc:", j);
 			}
-			b := malloc.Alloc(uint64(j));
+			if a := malloc.GetStats().Alloc; a != 0 {
+				panicln("no allocations but stats report", a, "bytes allocated");
+			}
+			b := malloc.Alloc(uintptr(j));
 			during := malloc.GetStats().Alloc;
 			malloc.Free(b);
 			if a := malloc.GetStats().Alloc; a != 0 {
-				panicln("malloc wrong count", a, "after", j, "during", during);
+				panic("allocated ", j, ": wrong stats: during=", during, " after=", a, " (want 0)");
 			}
 			bigger();
 		}
diff --git a/test/mallocrep1.go b/test/mallocrep1.go
index 5d17dc2c6d1..e78a9ce9ca5 100644
--- a/test/mallocrep1.go
+++ b/test/mallocrep1.go
@@ -44,7 +44,7 @@ func AllocAndFree(size, count int) {
 	}
 	n1 := stats.Alloc;
 	for i := 0; i < count; i++ {
-		b[i] = malloc.Alloc(uint64(size));
+		b[i] = malloc.Alloc(uintptr(size));
 		base, n := malloc.Lookup(b[i]);
 		if base != b[i] || !OkAmount(uintptr(size), n) {
 			panicln("lookup failed: got", base, n, "for", b[i]);
@@ -63,14 +63,14 @@ func AllocAndFree(size, count int) {
 		if *reverse {
 			i = count - 1 - j;
 		}
-		alloc := stats.Alloc;
+		alloc := uintptr(stats.Alloc);
 		base, n := malloc.Lookup(b[i]);
 		if base != b[i] || !OkAmount(uintptr(size), n) {
 			panicln("lookup failed: got", base, n, "for", b[i]);
 		}
 		malloc.Free(b[i]);
-		if stats.Alloc != alloc - uint64(n) {
-			panicln("free alloc got", stats.Alloc, "expected", alloc - uint64(n), "after free of", n);
+		if stats.Alloc != uint64(alloc - n) {
+			panicln("free alloc got", stats.Alloc, "expected", alloc - n, "after free of", n);
 		}
 		if malloc.GetStats().Sys > 1e9 {
 			panicln("too much memory allocated");
@@ -100,12 +100,12 @@ func main() {
 	}
 	for j := 1; j <= 1<<22; j<<=1 {
 		n := len(b);
-		max := uint64(1<<28);
+		max := uintptr(1<<28);
 		if !*longtest {
 			max = 1<<22;
 		}
-		if uint64(j)*uint64(n) > max {
-			n = int(max / uint64(j));
+		if uintptr(j)*uintptr(n) > max {
+			n = int(max / uintptr(j));
 		}
 		if n < 10 {
 			n = 10;
diff --git a/test/run b/test/run
index 5724449acbb..63dca3b42aa 100755
--- a/test/run
+++ b/test/run
@@ -67,6 +67,7 @@ done | # clean up some stack noise
 		s/ PC=0x[0-9a-f]*/ PC=xxx/
 		s/^pc: 0x[0-9a-f]*/pc: xxx/
 		/^Trace\/breakpoint trap/d
+		/^Trace\/BPT trap/d
 		/RUNFILE/ s/line 1: *[0-9]*/line 1: PID/
 		/^\$RUNFILE: line 1: PID Trace\/breakpoint trap/d' > run.out