diff --git a/libsysio/include/fs.h b/libsysio/include/fs.h
index 8c7e782501d90914642a733bc4a67f1bda9ecf80..95eab247ed65036da6b1dfd4501f238f8b2bb82b 100644
--- a/libsysio/include/fs.h
+++ b/libsysio/include/fs.h
@@ -167,6 +167,6 @@ extern struct filesys * _sysio_fs_new(struct filesys_ops *ops,
 				      unsigned mask,
 				      void *private);
 extern void _sysio_fs_gone(struct filesys *fs);
-#if ZERO_SUM_MEMORY
+#ifdef ZERO_SUM_MEMORY
 extern void _sysio_fssw_shutdown(void);
 #endif
diff --git a/libsysio/include/inode.h b/libsysio/include/inode.h
index a825fafcdec7f165832b7f7134a373d3c05d2b7e..7b2b9c671ef58c67776710e3d591bdedbbbbb3fb 100644
--- a/libsysio/include/inode.h
+++ b/libsysio/include/inode.h
@@ -416,7 +416,7 @@ extern TAILQ_HEAD(inodes_head, inode) _sysio_inodes;
 extern TAILQ_HEAD(pnodes_head, pnode) _sysio_pnodes;
 
 extern int _sysio_i_init(void);
-#if ZERO_SUM_MEMORY
+#ifdef ZERO_SUM_MEMORY
 extern void _sysio_i_shutdown(void);
 #endif
 extern struct inode *_sysio_i_new(struct filesys *fs,
diff --git a/libsysio/include/sysio-cmn.h b/libsysio/include/sysio-cmn.h
index cd977569974fc1c8ecf381b48e12e29462b05ccd..07b3339cb22e89ad1b8e3ca107a3afb2ddc6aa83 100644
--- a/libsysio/include/sysio-cmn.h
+++ b/libsysio/include/sysio-cmn.h
@@ -151,7 +151,7 @@ struct iovec;
 	} while(0) 
 
 /* Interface enter/leave hook functions  */
-#if SYSIO_TRACING
+#ifdef SYSIO_TRACING
 extern void *_sysio_entry_trace_q;
 extern void *_sysio_exit_trace_q;
 
diff --git a/libsysio/include/sysio.h b/libsysio/include/sysio.h
index 9d914b8a9a8333bdf105c4862ff6de9a01669374..770d741f3dbbdedf444a4d03eaa44054d6545410 100644
--- a/libsysio/include/sysio.h
+++ b/libsysio/include/sysio.h
@@ -112,7 +112,7 @@ struct intnl_stat;
 
 struct pnode;
 
-#if DEFER_INIT_CWD
+#ifdef DEFER_INIT_CWD
 extern const char *_sysio_init_cwd;
 #endif
 
@@ -151,7 +151,7 @@ extern char * _sysio_get_args(char *buf, struct option_value_info *vec);
 
 extern time_t _sysio_local_time(void);
 
-#if SYSIO_TRACING
+#ifdef SYSIO_TRACING
 extern void _sysio_cprintf(const char *fmt, ...);
 #endif