diff --git a/qa/kern/build.json b/qa/kern/build.json
index 3bc6203..4067bb2 100644
--- a/qa/kern/build.json
+++ b/qa/kern/build.json
@@ -8,6 +8,9 @@
 			"cp *.rc $JEHANNE/arch/$ARCH/qa/kern/",
 			"cp *.runner $JEHANNE/arch/$ARCH/qa/kern/"
 		],
+		"Disabled": [
+			"fork_chain.c"
+		],
 		"SourceFilesCmd": [
 			"alarm.c",
 			"args.c",
@@ -18,7 +21,6 @@
 			"execl.c",
 			"float.c",
 			"fork.c",
-			"fork_chain.c",
 			"frexp.c",
 			"getmainpid.c",
 			"getpid.c",
diff --git a/qa/lib/newlib/build.json b/qa/lib/newlib/build.json
index 7a0bab0..e6be66a 100644
--- a/qa/lib/newlib/build.json
+++ b/qa/lib/newlib/build.json
@@ -76,16 +76,18 @@
 		"SourceFiles": [
 			"libposix_sigchld.c"
 		],
-		"SourceFilesCmd": [
-			"000-hello.c",
+		"Disabled": [
 			"010-fork.c",
 			"020-waitpid.c",
-			"100-files.c",
-			"101-files.c",
 			"200-signals.c",
 			"201-signals.c",
 			"202-signals.c",
 			"203-signals.c"
+		],
+		"SourceFilesCmd": [
+			"000-hello.c",
+			"100-files.c",
+			"101-files.c"
 		]
 	},
 	"NewlibTestsuite": {
diff --git a/sys/src/kern/amd64/mmu.c b/sys/src/kern/amd64/mmu.c
index 08f8424..38a695a 100644
--- a/sys/src/kern/amd64/mmu.c
+++ b/sys/src/kern/amd64/mmu.c
@@ -5,7 +5,7 @@
 #include "fns.h"
 
 #include "amd64.h"
-#define DO_mmuptpcheck
+//#define DO_mmuptpcheck
 
 //#undef DBG
 //#define DBG(...)	jehanne_print(__VA_ARGS__)
@@ -37,8 +37,6 @@ static struct{
 } ptpfreelist;
 int	ptpcount;
 
-#define DO_mmuptpcheck
-
 #ifdef DO_mmuptpcheck
 static void mmuptpcheck(Proc*);
 #endif
@@ -785,7 +783,7 @@ mmuptpcheck(Proc *proc)
 				}
 				if(idx[i] == p->ptoff){
 					dumpmmu(proc);
-					panic("ptcheck: dup daddr");
+					panic("ptcheck: dup ptoff %d (%#p == %#p)", p->ptoff, pgs[i], p);
 				}
 			}
 			if(npgs >= Tsize)