diff --git a/src/Mamfile b/src/Mamfile
index 71f83bac7..fdf8ec6f0 100644
--- a/src/Mamfile
+++ b/src/Mamfile
@@ -1,4 +1,13 @@
 info mam static
+note *
+note * This build file is in the Make Abstract Machine (MAM) language. It was
+note * first generated by nmake, but in the ksh 93u+m distribution we maintain
+note * it manually because nmake had too many problems to keep using. The
+note * Mamfiles are processed by mamake (src/cmd/INIT/mamake.c); we added
+note * support for indentation to improve readability. The language is
+note * documented in Glenn Fowler's paper "A Make Abstract Machine":
+note * http://web.archive.org/web/20041227143022/http://www2.research.att.com/~gsf/mam/mam.html
+note *
 note source level :MAKE: equivalent
 make install
 	make all
diff --git a/src/cmd/INIT/Mamfile b/src/cmd/INIT/Mamfile
index fa800dce2..4dfe4c746 100644
--- a/src/cmd/INIT/Mamfile
+++ b/src/cmd/INIT/Mamfile
@@ -1,4 +1,13 @@
 info mam static 00000 1994-07-17 make (AT&T Research) 5.7 2012-06-20
+note *
+note * This build file is in the Make Abstract Machine (MAM) language. It was
+note * first generated by nmake, but in the ksh 93u+m distribution we maintain
+note * it manually because nmake had too many problems to keep using. The
+note * Mamfiles are processed by mamake (src/cmd/INIT/mamake.c); we added
+note * support for indentation to improve readability. The language is
+note * documented in Glenn Fowler's paper "A Make Abstract Machine":
+note * http://web.archive.org/web/20041227143022/http://www2.research.att.com/~gsf/mam/mam.html
+note *
 setv INSTALLROOT ../../..
 setv PACKAGEROOT ../../../../..
 setv AR ${mam_cc_AR} ${mam_cc_AR_ARFLAGS}
diff --git a/src/cmd/INIT/mamake.c b/src/cmd/INIT/mamake.c
index a8d0ecb91..4bcca91f5 100644
--- a/src/cmd/INIT/mamake.c
+++ b/src/cmd/INIT/mamake.c
@@ -19,7 +19,6 @@
 ***********************************************************************/
 #pragma prototyped
 #pragma clang diagnostic ignored "-Wparentheses"
-#pragma clang diagnostic ignored "-Wunused-value"
 
 /*
  * mamake -- MAM make
diff --git a/src/cmd/Mamfile b/src/cmd/Mamfile
index 25c98068c..3d2449604 100644
--- a/src/cmd/Mamfile
+++ b/src/cmd/Mamfile
@@ -1,4 +1,13 @@
 info mam static
+note *
+note * This build file is in the Make Abstract Machine (MAM) language. It was
+note * first generated by nmake, but in the ksh 93u+m distribution we maintain
+note * it manually because nmake had too many problems to keep using. The
+note * Mamfiles are processed by mamake (src/cmd/INIT/mamake.c); we added
+note * support for indentation to improve readability. The language is
+note * documented in Glenn Fowler's paper "A Make Abstract Machine":
+note * http://web.archive.org/web/20041227143022/http://www2.research.att.com/~gsf/mam/mam.html
+note *
 note component level :MAKE: equivalent
 make install
 	make all
diff --git a/src/cmd/builtin/Mamfile b/src/cmd/builtin/Mamfile
index 2272cef6c..531487e73 100644
--- a/src/cmd/builtin/Mamfile
+++ b/src/cmd/builtin/Mamfile
@@ -1,4 +1,13 @@
 info mam static 00000 1994-07-17 make (AT&T Research) 5.7 2012-06-20
+note *
+note * This build file is in the Make Abstract Machine (MAM) language. It was
+note * first generated by nmake, but in the ksh 93u+m distribution we maintain
+note * it manually because nmake had too many problems to keep using. The
+note * Mamfiles are processed by mamake (src/cmd/INIT/mamake.c); we added
+note * support for indentation to improve readability. The language is
+note * documented in Glenn Fowler's paper "A Make Abstract Machine":
+note * http://web.archive.org/web/20041227143022/http://www2.research.att.com/~gsf/mam/mam.html
+note *
 setv INSTALLROOT ../../..
 setv PACKAGE_ast_INCLUDE ${INSTALLROOT}/include/ast
 setv PACKAGE_ast_LIB ${INSTALLROOT}/lib
diff --git a/src/cmd/ksh93/Mamfile b/src/cmd/ksh93/Mamfile
index d13f37921..0e84b5c6c 100644
--- a/src/cmd/ksh93/Mamfile
+++ b/src/cmd/ksh93/Mamfile
@@ -1,4 +1,13 @@
 info mam static 00000 1994-07-17 make (AT&T Research) 5.7 2012-06-20
+note *
+note * This build file is in the Make Abstract Machine (MAM) language. It was
+note * first generated by nmake, but in the ksh 93u+m distribution we maintain
+note * it manually because nmake had too many problems to keep using. The
+note * Mamfiles are processed by mamake (src/cmd/INIT/mamake.c); we added
+note * support for indentation to improve readability. The language is
+note * documented in Glenn Fowler's paper "A Make Abstract Machine":
+note * http://web.archive.org/web/20041227143022/http://www2.research.att.com/~gsf/mam/mam.html
+note *
 setv INSTALLROOT ../../..
 setv PACKAGE_ast_INCLUDE ${INSTALLROOT}/include/ast
 setv PACKAGE_ast_LIB ${INSTALLROOT}/lib
diff --git a/src/lib/Mamfile b/src/lib/Mamfile
index 25c98068c..3d2449604 100644
--- a/src/lib/Mamfile
+++ b/src/lib/Mamfile
@@ -1,4 +1,13 @@
 info mam static
+note *
+note * This build file is in the Make Abstract Machine (MAM) language. It was
+note * first generated by nmake, but in the ksh 93u+m distribution we maintain
+note * it manually because nmake had too many problems to keep using. The
+note * Mamfiles are processed by mamake (src/cmd/INIT/mamake.c); we added
+note * support for indentation to improve readability. The language is
+note * documented in Glenn Fowler's paper "A Make Abstract Machine":
+note * http://web.archive.org/web/20041227143022/http://www2.research.att.com/~gsf/mam/mam.html
+note *
 note component level :MAKE: equivalent
 make install
 	make all
diff --git a/src/lib/libast/Mamfile b/src/lib/libast/Mamfile
index 8e5320b2f..8d6df8325 100644
--- a/src/lib/libast/Mamfile
+++ b/src/lib/libast/Mamfile
@@ -1,4 +1,13 @@
 info mam static 00000 1994-07-17 make (AT&T Research) 5.7 2012-06-20
+note *
+note * This build file is in the Make Abstract Machine (MAM) language. It was
+note * first generated by nmake, but in the ksh 93u+m distribution we maintain
+note * it manually because nmake had too many problems to keep using. The
+note * Mamfiles are processed by mamake (src/cmd/INIT/mamake.c); we added
+note * support for indentation to improve readability. The language is
+note * documented in Glenn Fowler's paper "A Make Abstract Machine":
+note * http://web.archive.org/web/20041227143022/http://www2.research.att.com/~gsf/mam/mam.html
+note *
 setv INSTALLROOT ../../..
 setv PACKAGEROOT ../../../../..
 setv AR ${mam_cc_AR} ${mam_cc_AR_ARFLAGS}
diff --git a/src/lib/libcmd/Mamfile b/src/lib/libcmd/Mamfile
index 8f8c8e854..3983da737 100644
--- a/src/lib/libcmd/Mamfile
+++ b/src/lib/libcmd/Mamfile
@@ -1,4 +1,13 @@
 info mam static 00000 1994-07-17 make (AT&T Research) 5.7 2012-06-20
+note *
+note * This build file is in the Make Abstract Machine (MAM) language. It was
+note * first generated by nmake, but in the ksh 93u+m distribution we maintain
+note * it manually because nmake had too many problems to keep using. The
+note * Mamfiles are processed by mamake (src/cmd/INIT/mamake.c); we added
+note * support for indentation to improve readability. The language is
+note * documented in Glenn Fowler's paper "A Make Abstract Machine":
+note * http://web.archive.org/web/20041227143022/http://www2.research.att.com/~gsf/mam/mam.html
+note *
 setv INSTALLROOT ../../..
 setv PACKAGE_ast_INCLUDE ${INSTALLROOT}/include/ast
 setv PACKAGE_ast_LIB ${INSTALLROOT}/lib
diff --git a/src/lib/libdll/Mamfile b/src/lib/libdll/Mamfile
index e5f833e62..5a36e3bad 100644
--- a/src/lib/libdll/Mamfile
+++ b/src/lib/libdll/Mamfile
@@ -1,4 +1,13 @@
 info mam static 00000 1994-07-17 make (AT&T Research) 5.7 2012-06-20
+note *
+note * This build file is in the Make Abstract Machine (MAM) language. It was
+note * first generated by nmake, but in the ksh 93u+m distribution we maintain
+note * it manually because nmake had too many problems to keep using. The
+note * Mamfiles are processed by mamake (src/cmd/INIT/mamake.c); we added
+note * support for indentation to improve readability. The language is
+note * documented in Glenn Fowler's paper "A Make Abstract Machine":
+note * http://web.archive.org/web/20041227143022/http://www2.research.att.com/~gsf/mam/mam.html
+note *
 setv INSTALLROOT ../../..
 setv PACKAGE_ast_INCLUDE ${INSTALLROOT}/include/ast
 setv PACKAGE_ast_LIB ${INSTALLROOT}/lib
diff --git a/src/lib/libsum/Mamfile b/src/lib/libsum/Mamfile
index b553572d4..2682c92b6 100644
--- a/src/lib/libsum/Mamfile
+++ b/src/lib/libsum/Mamfile
@@ -1,4 +1,13 @@
 info mam static 00000 1994-07-17 make (AT&T Research) 5.7 2012-06-20
+note *
+note * This build file is in the Make Abstract Machine (MAM) language. It was
+note * first generated by nmake, but in the ksh 93u+m distribution we maintain
+note * it manually because nmake had too many problems to keep using. The
+note * Mamfiles are processed by mamake (src/cmd/INIT/mamake.c); we added
+note * support for indentation to improve readability. The language is
+note * documented in Glenn Fowler's paper "A Make Abstract Machine":
+note * http://web.archive.org/web/20041227143022/http://www2.research.att.com/~gsf/mam/mam.html
+note *
 setv INSTALLROOT ../../..
 setv PACKAGE_ast_INCLUDE ${INSTALLROOT}/include/ast
 setv PACKAGE_ast_LIB ${INSTALLROOT}/lib