7 files changed, 34 insertions, 10 deletions
diff --git a/src/internal/slibtool_driver_impl.h b/src/internal/slibtool_driver_impl.h
index 54a5f05..47c854e 100644
--- a/src/internal/slibtool_driver_impl.h
+++ b/src/internal/slibtool_driver_impl.h
@@ -1,3 +1,9 @@
+/*******************************************************************/
+/*  slibtool: a skinny libtool implementation, written in C        */
+/*  Copyright (C) 2016--2018  Z. Gilboa                            */
+/*  Released under the Standard MIT License; see COPYING.SLIBTOOL. */
+/*******************************************************************/
+
 #ifndef SLIBTOOL_DRIVER_IMPL_H
 #define SLIBTOOL_DRIVER_IMPL_H
 
diff --git a/src/internal/slibtool_errinfo_impl.h b/src/internal/slibtool_errinfo_impl.h
index 58d6aff..a1d3b61 100644
--- a/src/internal/slibtool_errinfo_impl.h
+++ b/src/internal/slibtool_errinfo_impl.h
@@ -4,6 +4,9 @@
 /*  Released under the Standard MIT License; see COPYING.SLIBTOOL. */
 /*******************************************************************/
 
+#ifndef SLIBTOOL_ERRINFO_IMPL_H
+#define SLIBTOOL_ERRINFO_IMPL_H
+
 #include <errno.h>
 #include <slibtool/slibtool.h>
 
@@ -78,3 +81,5 @@ int slbt_record_error(
 		__LINE__,                 \
 		SLBT_ERROR_NESTED,        \
 		0)
+
+#endif
diff --git a/src/internal/slibtool_metafile_impl.h b/src/internal/slibtool_metafile_impl.h
index 62a96ad..bd78b09 100644
--- a/src/internal/slibtool_metafile_impl.h
+++ b/src/internal/slibtool_metafile_impl.h
@@ -1,8 +1,5 @@
-/*******************************************************************/
-/*  slibtool: a skinny libtool implementation, written in C        */
-/*  Copyright (C) 2016--2018  Z. Gilboa                            */
-/*  Released under the Standard MIT License; see COPYING.SLIBTOOL. */
-/*******************************************************************/
+#ifndef SLIBTOOL_METAFILE_IMPL_H
+#define SLIBTOOL_METAFILE_IMPL_H
 
 #include <slibtool/slibtool.h>
 
@@ -17,3 +14,5 @@ int  slbt_create_library_wrapper(
 	char *				soname,
 	char *				soxyz,
 	char *				solnk);
+
+#endif
diff --git a/src/internal/slibtool_mkdir_impl.h b/src/internal/slibtool_mkdir_impl.h
index 4cb3a27..5fb8895 100644
--- a/src/internal/slibtool_mkdir_impl.h
+++ b/src/internal/slibtool_mkdir_impl.h
@@ -4,6 +4,9 @@
 /*  Released under the Standard MIT License; see COPYING.SLIBTOOL. */
 /*******************************************************************/
 
+#ifndef SLIBTOOL_MKDIR_IMPL_H
+#define SLIBTOOL_MKDIR_IMPL_H
+
 #include <errno.h>
 #include <unistd.h>
 
@@ -23,3 +26,5 @@ static inline int slbt_mkdir(const char * path)
 
 	return 0;
 }
+
+#endif
diff --git a/src/internal/slibtool_readlink_impl.h b/src/internal/slibtool_readlink_impl.h
index 191850c..c29b2d2 100644
--- a/src/internal/slibtool_readlink_impl.h
+++ b/src/internal/slibtool_readlink_impl.h
@@ -4,6 +4,9 @@
 /*  Released under the Standard MIT License; see COPYING.SLIBTOOL. */
 /*******************************************************************/
 
+#ifndef SLIBTOOL_READLINK_IMPL_H
+#define SLIBTOOL_READLINK_IMPL_H
+
 #include <unistd.h>
 
 static inline int slbt_readlink(
@@ -22,3 +25,5 @@ static inline int slbt_readlink(
 		return 0;
 	}
 }
+
+#endif
diff --git a/src/internal/slibtool_spawn_impl.h b/src/internal/slibtool_spawn_impl.h
index 35aae9f..e4efda1 100644
--- a/src/internal/slibtool_spawn_impl.h
+++ b/src/internal/slibtool_spawn_impl.h
@@ -4,6 +4,9 @@
 /*  Released under the Standard MIT License; see COPYING.SLIBTOOL. */
 /*******************************************************************/
 
+#ifndef SLIBTOOL_SPAWN_IMPL_H
+#define SLIBTOOL_SPAWN_IMPL_H
+
 #include <limits.h>
 #include <unistd.h>
 #include <stdbool.h>
@@ -73,3 +76,5 @@ static inline int slbt_spawn(
 
 	return 0;
 }
+
+#endif
diff --git a/src/internal/slibtool_symlink_impl.h b/src/internal/slibtool_symlink_impl.h
index 8b418a1..9393a17 100644
--- a/src/internal/slibtool_symlink_impl.h
+++ b/src/internal/slibtool_symlink_impl.h
@@ -1,8 +1,5 @@
-/*******************************************************************/
-/*  slibtool: a skinny libtool implementation, written in C        */
-/*  Copyright (C) 2016--2018  Z. Gilboa                            */
-/*  Released under the Standard MIT License; see COPYING.SLIBTOOL. */
-/*******************************************************************/
+#ifndef SLIBTOOL_SYMLINK_IMPL_H
+#define SLIBTOOL_SYMLINK_IMPL_H
 
 #include <stdbool.h>
 #include <slibtool/slibtool.h>
@@ -15,3 +12,5 @@ int slbt_create_symlink(
 	bool				flawrapper);
 
 int slbt_symlink_is_a_placeholder(char * lnkpath);
+
+#endif