diff --git a/src/pkg/runtime/mem_darwin.c b/src/pkg/runtime/mem_darwin.c
index fe99c1aff15..47fe2a525ff 100644
--- a/src/pkg/runtime/mem_darwin.c
+++ b/src/pkg/runtime/mem_darwin.c
@@ -44,7 +44,7 @@ runtime·SysFree(void *v, uintptr n, uint64 *stat)
 void
 runtime·SysFault(void *v, uintptr n)
 {
-	runtime·mmap(v, n, PROT_NONE, 0, -1, 0);
+	runtime·mmap(v, n, PROT_NONE, MAP_ANON|MAP_PRIVATE|MAP_FIXED, -1, 0);
 }
 
 void*
diff --git a/src/pkg/runtime/mem_dragonfly.c b/src/pkg/runtime/mem_dragonfly.c
index f19a39950b2..ada820c2de8 100644
--- a/src/pkg/runtime/mem_dragonfly.c
+++ b/src/pkg/runtime/mem_dragonfly.c
@@ -48,7 +48,7 @@ runtime·SysFree(void *v, uintptr n, uint64 *stat)
 void
 runtime·SysFault(void *v, uintptr n)
 {
-	runtime·mmap(v, n, PROT_NONE, 0, -1, 0);
+	runtime·mmap(v, n, PROT_NONE, MAP_ANON|MAP_PRIVATE|MAP_FIXED, -1, 0);
 }
 
 void*
diff --git a/src/pkg/runtime/mem_freebsd.c b/src/pkg/runtime/mem_freebsd.c
index b8895567d21..1d6024013b8 100644
--- a/src/pkg/runtime/mem_freebsd.c
+++ b/src/pkg/runtime/mem_freebsd.c
@@ -48,7 +48,7 @@ runtime·SysFree(void *v, uintptr n, uint64 *stat)
 void
 runtime·SysFault(void *v, uintptr n)
 {
-	runtime·mmap(v, n, PROT_NONE, 0, -1, 0);
+	runtime·mmap(v, n, PROT_NONE, MAP_ANON|MAP_PRIVATE|MAP_FIXED, -1, 0);
 }
 
 void*
diff --git a/src/pkg/runtime/mem_linux.c b/src/pkg/runtime/mem_linux.c
index bab05011ff1..2ead204101f 100644
--- a/src/pkg/runtime/mem_linux.c
+++ b/src/pkg/runtime/mem_linux.c
@@ -95,7 +95,7 @@ runtime·SysFree(void *v, uintptr n, uint64 *stat)
 void
 runtime·SysFault(void *v, uintptr n)
 {
-	runtime·mmap(v, n, PROT_NONE, 0, -1, 0);
+	runtime·mmap(v, n, PROT_NONE, MAP_ANON|MAP_PRIVATE|MAP_FIXED, -1, 0);
 }
 
 void*
diff --git a/src/pkg/runtime/mem_nacl.c b/src/pkg/runtime/mem_nacl.c
index b3cf91d7f0e..c743259cc06 100644
--- a/src/pkg/runtime/mem_nacl.c
+++ b/src/pkg/runtime/mem_nacl.c
@@ -56,7 +56,7 @@ runtime·SysFree(void *v, uintptr n, uint64 *stat)
 void
 runtime·SysFault(void *v, uintptr n)
 {
-	runtime·mmap(v, n, PROT_NONE, 0, -1, 0);
+	runtime·mmap(v, n, PROT_NONE, MAP_ANON|MAP_PRIVATE|MAP_FIXED, -1, 0);
 }
 
 void*
diff --git a/src/pkg/runtime/mem_netbsd.c b/src/pkg/runtime/mem_netbsd.c
index 5ad7937d0f2..ed0a0583699 100644
--- a/src/pkg/runtime/mem_netbsd.c
+++ b/src/pkg/runtime/mem_netbsd.c
@@ -48,7 +48,7 @@ runtime·SysFree(void *v, uintptr n, uint64 *stat)
 void
 runtime·SysFault(void *v, uintptr n)
 {
-	runtime·mmap(v, n, PROT_NONE, 0, -1, 0);
+	runtime·mmap(v, n, PROT_NONE, MAP_ANON|MAP_PRIVATE|MAP_FIXED, -1, 0);
 }
 
 void*
diff --git a/src/pkg/runtime/mem_openbsd.c b/src/pkg/runtime/mem_openbsd.c
index 5ad7937d0f2..ed0a0583699 100644
--- a/src/pkg/runtime/mem_openbsd.c
+++ b/src/pkg/runtime/mem_openbsd.c
@@ -48,7 +48,7 @@ runtime·SysFree(void *v, uintptr n, uint64 *stat)
 void
 runtime·SysFault(void *v, uintptr n)
 {
-	runtime·mmap(v, n, PROT_NONE, 0, -1, 0);
+	runtime·mmap(v, n, PROT_NONE, MAP_ANON|MAP_PRIVATE|MAP_FIXED, -1, 0);
 }
 
 void*
diff --git a/src/pkg/runtime/mem_solaris.c b/src/pkg/runtime/mem_solaris.c
index 2379cdff9f8..f82a25b0312 100644
--- a/src/pkg/runtime/mem_solaris.c
+++ b/src/pkg/runtime/mem_solaris.c
@@ -49,7 +49,7 @@ runtime·SysFree(void *v, uintptr n, uint64 *stat)
 void
 runtime·SysFault(void *v, uintptr n)
 {
-	runtime·mmap(v, n, PROT_NONE, 0, -1, 0);
+	runtime·mmap(v, n, PROT_NONE, MAP_ANON|MAP_PRIVATE|MAP_FIXED, -1, 0);
 }
 
 void*
diff --git a/src/pkg/runtime/mem_windows.c b/src/pkg/runtime/mem_windows.c
index 3c6fef60cff..c0820082599 100644
--- a/src/pkg/runtime/mem_windows.c
+++ b/src/pkg/runtime/mem_windows.c
@@ -66,11 +66,8 @@ runtime·SysFree(void *v, uintptr n, uint64 *stat)
 void
 runtime·SysFault(void *v, uintptr n)
 {
-	uintptr r, old;
-
-	r = (uintptr)runtime·stdcall(runtime·VirtualProtect, 4, v, n, (uintptr)PAGE_NOACCESS, &old);
-	if(r == 0)
-		runtime·throw("runtime: failed to protect pages");
+	// SysUnused makes the memory inaccessible and prevents its reuse
+	runtime·SysUnused(v, n);
 }
 
 void*