diff --git a/libsel4simple/arch_include/arm/simple/arch/simple.h b/libsel4simple/arch_include/arm/simple/arch/simple.h
index dac7eb128..1f95d2894 100644
--- a/libsel4simple/arch_include/arm/simple/arch/simple.h
+++ b/libsel4simple/arch_include/arm/simple/arch/simple.h
@@ -16,7 +16,13 @@
 
 /* Simple does not address initial null caps, including seL4_CapNull.
  * seL4_CapIOSpace, seL4_CapIOPortControl are null on architectures other than x86 */
-#define SIMPLE_SKIPPED_INIT_CAPS 3
+#ifdef CONFIG_KERNEL_MCS
+#define SKIP_THREADSC 0
+#else
+#define SKIP_THREADSC 1
+#endif
+
+#define SIMPLE_SKIPPED_INIT_CAPS (3 + SKIP_THREADSC)
 
 /* Request a cap to a specific IRQ number on the system
  *
diff --git a/libsel4simple/arch_include/x86/simple/arch/simple.h b/libsel4simple/arch_include/x86/simple/arch/simple.h
index b1d396ebd..f8c40efe9 100644
--- a/libsel4simple/arch_include/x86/simple/arch/simple.h
+++ b/libsel4simple/arch_include/x86/simple/arch/simple.h
@@ -16,12 +16,20 @@
 
 /* Simple does not address initial null caps, including seL4_CapNull */
 #ifdef CONFIG_IOMMU
-#define SIMPLE_SKIPPED_INIT_CAPS 1
+#define SKIP_IOSPACE 0
 #else
 /* seL4_CapIOSpace is null if IOMMU isn't supported */
-#define SIMPLE_SKIPPED_INIT_CAPS 2
+#define SKIP_IOSPACE 1
 #endif
 
+#ifdef CONFIG_KERNEL_MCS
+#define SKIP_THREADSC 0
+#else
+#define SKIP_THREADSC 1
+#endif
+
+#define SIMPLE_SKIPPED_INIT_CAPS (1 + SKIP_IOSPACE + SKIP_THREADSC)
+
 /**
  * Request a cap to the IOPorts
  *