diff --git a/base-nova/include/32bit/nova/syscalls.h b/base-nova/include/32bit/nova/syscalls.h
index 66f58fbf39..20ba7b6331 100644
--- a/base-nova/include/32bit/nova/syscalls.h
+++ b/base-nova/include/32bit/nova/syscalls.h
@@ -247,11 +247,6 @@ namespace Nova {
 		return status;
 	}
 
-	/**
-	 * Semaphore operations
-	 */
-	enum Sem_op { SEMAPHORE_UP = 0, SEMAPHORE_DOWN = 1 };
-
 
 	ALWAYS_INLINE
 	inline uint8_t sm_ctrl(unsigned sm, Sem_op op)
diff --git a/base-nova/include/64bit/nova/syscalls.h b/base-nova/include/64bit/nova/syscalls.h
index 345c9f33a6..31ce1fa695 100644
--- a/base-nova/include/64bit/nova/syscalls.h
+++ b/base-nova/include/64bit/nova/syscalls.h
@@ -211,11 +211,6 @@ namespace Nova {
 		return res;
 	}
 
-	/**
-	 * Semaphore operations
-	 */
-	enum Sem_op { SEMAPHORE_UP = 0, SEMAPHORE_DOWN = 1 };
-
 
 	ALWAYS_INLINE
 	inline uint8_t sm_ctrl(mword_t sm, Sem_op op)
diff --git a/base-nova/include/nova/syscall-generic.h b/base-nova/include/nova/syscall-generic.h
index 82e69c1c06..462b10773b 100644
--- a/base-nova/include/nova/syscall-generic.h
+++ b/base-nova/include/nova/syscall-generic.h
@@ -109,6 +109,12 @@ namespace Nova {
 	} __attribute__((packed));
 
 
+	/**
+	 * Semaphore operations
+	 */
+	enum Sem_op { SEMAPHORE_UP = 0U, SEMAPHORE_DOWN = 1U, SEMAPHORE_DOWNZERO = 0x3U };
+
+
 	class Descriptor
 	{
 		protected: