diff --git a/hermit/arch/x86/kernel/apic.c b/hermit/arch/x86/kernel/apic.c
index fa6d77c87..9e583235c 100644
--- a/hermit/arch/x86/kernel/apic.c
+++ b/hermit/arch/x86/kernel/apic.c
@@ -50,7 +50,7 @@ extern const void kernel_start;
 
 #define IOAPIC_ADDR	((size_t) &kernel_start - 2*PAGE_SIZE)
 #define LAPIC_ADDR	((size_t) &kernel_start - 1*PAGE_SIZE)
-#define MAX_APIC_CORES	128
+#define MAX_APIC_CORES	MAX_CORES
 
 // IO APIC MMIO structure: write reg, then read or write data.
 typedef struct {
diff --git a/hermit/include/hermit/config.h b/hermit/include/hermit/config.h
index 45dc326ab..09a589b06 100644
--- a/hermit/include/hermit/config.h
+++ b/hermit/include/hermit/config.h
@@ -32,7 +32,7 @@
 extern "C" {
 #endif
 
-#define MAX_CORES		64
+#define MAX_CORES		128
 #define MAX_TASKS		(MAX_CORES*2+2)
 #define MAX_ISLE		8
 #define MAX_FNAME		128
@@ -50,7 +50,6 @@ extern "C" {
 
 #define BYTE_ORDER		LITTLE_ENDIAN
 
-#define LIBOS
 #define DYNAMIC_TICKS
 
 #define BUILTIN_EXPECT(exp, b) 	__builtin_expect((exp), (b))
diff --git a/hermit/kernel/tasks.c b/hermit/kernel/tasks.c
index 9aae78185..fe45ba017 100644
--- a/hermit/kernel/tasks.c
+++ b/hermit/kernel/tasks.c
@@ -409,8 +409,10 @@ int clone_task(tid_t* id, entry_point_t ep, void* arg, uint8_t prio)
 		kprintf("start new thread %d on core %d with stack address %p\n", i, core_id, stack);
 
 out:
-	if (ret)
+	if (ret) {
 		destroy_stack(stack, DEFAULT_STACK_SIZE);
+		destroy_stack(ist, KERNEL_STACK_SIZE);
+	}
 
 #if 0
 	if (core_id != CORE_ID)
@@ -510,6 +512,7 @@ out:
 
 	if (ret) {
 		destroy_stack(stack, DEFAULT_STACK_SIZE);
+		destroy_stack(ist, KERNEL_STACK_SIZE);
 		kfree(counter);
 	}