diff --git a/rules.mak b/rules.mak
index 633a81c1..66f719d1 100644
--- a/rules.mak
+++ b/rules.mak
@@ -16,7 +16,7 @@ depend: ${DEPEND_FILE}
 # corrupting the output, the final MV is transactional. If that is needed
 # it indicates a missing dependency somewhere in a upstream/parent Makefile.
 ${DEPEND_FILE}: ${DEPSRCS}
-	${CC} ${CFLAGS} ${CPPFLAGS} ${DFLAGS} ${DEPEND_FLAG} ${DEPSRCS} > ${DEPEND_FILE}$$PPID.tmp
+	${CC} ${CFLAGS} ${CPPFLAGS} ${DFLAGS} ${DEPEND_FLAG} $(addprefix $(srcdir)/,${DEPSRCS}) > ${DEPEND_FILE}$$PPID.tmp
 	${SED} -e "/#/D" -e "/ \//s/ \/.*\.h//" -e "/  \\\/D" -i ${DEPEND_FILE}$$PPID.tmp
 	${MV} -f ${DEPEND_FILE}$$PPID.tmp ${DEPEND_FILE}
 
@@ -26,7 +26,7 @@ ${DEPEND_FILE}: ${DEPSRCS}
 %.o: %.c
 	@echo --- compiling ${MODULE}/$*.o
 	${RM} $*.o
-	${CC} ${CFLAGS} ${CPPFLAGS} ${DFLAGS}  -c $*.c
+	${CC} ${CFLAGS} ${CPPFLAGS} ${DFLAGS}  -c $< -o $@
 
 lib${MODULE}.o: ${OBJS}
 	@echo --- linking lib${MODULE}.o
@@ -55,7 +55,7 @@ clean:
 	${RM} ${CLEANS}
 
 tags: ${SRCS} ${LIB_SRCS}
-	ctags ${SRCS} ${LIB_SRCS}
+	ctags $(addprefix $(srcdir)/,${SRCS} ${LIB_SRCS})
 
 # Depends are a somewhat optional part of the build process that are only useful when incremental
 # building.  If the file is here it's here, if not continue with build optimistically
diff --git a/scripts/configure b/scripts/configure
index ffb0643e..08d8731b 100755
--- a/scripts/configure
+++ b/scripts/configure
@@ -9300,6 +9300,8 @@ ac_config_files="$ac_config_files defs.mak:scripts/defs.mak.in"
 
 ac_config_files="$ac_config_files scripts/makedbh:scripts/makedbh.in"
 
+ac_config_files="$ac_config_files rules.mak:rules.mak"
+
 cat >confcache <<\_ACEOF
 # This file is a shell script that caches the results of configure
 # tests run on this system so they can be shared between configure
@@ -10009,6 +10011,7 @@ do
   case $ac_config_target in
     "defs.mak") CONFIG_FILES="$CONFIG_FILES defs.mak:scripts/defs.mak.in" ;;
     "scripts/makedbh") CONFIG_FILES="$CONFIG_FILES scripts/makedbh:scripts/makedbh.in" ;;
+    "rules.mak") CONFIG_FILES="$CONFIG_FILES rules.mak:rules.mak" ;;
 
   *) as_fn_error $? "invalid argument: \`$ac_config_target'" "$LINENO" 5;;
   esac
diff --git a/scripts/configure.in b/scripts/configure.in
index 43f76843..9cc46c81 100644
--- a/scripts/configure.in
+++ b/scripts/configure.in
@@ -1982,6 +1982,10 @@ dnl build directory (config.status' CWD): defs.mak at the build top, makedbh
 dnl under build/scripts/ (matching ${SCRIPTS}/makedbh = ${MAGICDIR}/scripts).
 AC_CONFIG_FILES([defs.mak:scripts/defs.mak.in])
 AC_CONFIG_FILES([scripts/makedbh:scripts/makedbh.in], [chmod +x scripts/makedbh])
+dnl Copy rules.mak into the build top (it has no @...@ substitutions; this just
+dnl places it next to the generated defs.mak so a single ${MAGICDIR} resolves
+dnl both `include`s in every subdir Makefile out-of-tree).
+AC_CONFIG_FILES([rules.mak:rules.mak])
 AC_OUTPUT
 
 dnl 
diff --git a/scripts/defs.mak.in b/scripts/defs.mak.in
index 26209659..2ca9cc5d 100755
--- a/scripts/defs.mak.in
+++ b/scripts/defs.mak.in
@@ -8,6 +8,27 @@
 
 SHELL                  = @SHELL@
 
+# --- out-of-tree (VPATH) support ------------------------------------------
+# MAGICDIR is set by each subdir Makefile to the relative path back to the
+# *build* top (that is where the generated defs.mak / rules.mak live, and where
+# the generated database/database.h is written).  MAGICSRC is the absolute path
+# to the *source* top.  For an in-tree build the two trees coincide.
+MAGICSRC               = @abs_top_srcdir@
+
+# Derive this module's source directory (and VPATH) from where make is running
+# (CURDIR, a build directory) relative to the build top (abspath of MAGICDIR):
+#   build top  = $(abspath $(MAGICDIR))
+#   subpath    = "/tiles", or "" at the top
+#   srcdir     = $(MAGICSRC)$(subpath)
+BUILD_TOP              := $(abspath $(MAGICDIR))
+# Anchored prefix strip (patsubst matches the whole word, so BUILD_TOP must be a
+# leading prefix): "" at the build top, "/tiles" in a subdir.  Unlike $(subst …)
+# this cannot mis-fire if BUILD_TOP happens to recur later in the path.
+MODULE_SUBPATH         := $(patsubst $(BUILD_TOP)%,%,$(CURDIR))
+srcdir                 := $(MAGICSRC)$(MODULE_SUBPATH)
+VPATH                  := $(srcdir)
+# --------------------------------------------------------------------------
+
 prefix = @prefix@
 exec_prefix = @exec_prefix@
 bindir = @bindir@
@@ -79,9 +100,9 @@ LIB_SPECS_GRNULL       = @LIB_SPECS_GRNULL@
 WISH_EXE	       = @WISH_EXE@
 TCL_LIB_DIR	       = @TCL_LIB_DIR@
 
-MAGIC_VERSION	       ?= $(shell cat ${MAGICDIR}/VERSION | cut -d. -f1-2)
-MAGIC_REVISION	       ?= $(shell cat ${MAGICDIR}/VERSION | cut -d. -f3)
-MAGIC_COMMIT	       ?= $(shell git rev-parse HEAD)
+MAGIC_VERSION	       ?= $(shell cat ${MAGICSRC}/VERSION | cut -d. -f1-2)
+MAGIC_REVISION	       ?= $(shell cat ${MAGICSRC}/VERSION | cut -d. -f3)
+MAGIC_COMMIT	       ?= $(shell git -C ${MAGICSRC} rev-parse HEAD)
 MAGIC_BUILDDATE	       ?= $(shell date | tr -d '\r\n')
 
 # This allow inheritence of the values from toplevel Makefile
@@ -111,7 +132,10 @@ CXX		       = @CXX@
 ###   Status: NOT-STABILITY-AFFECTING (if your binary links you are good to continue)
 #FEATURE_FLAGS += -DSUPPORT_REMOVE_MALLOC_LEGACY
 
-CPPFLAGS               = -I${MAGICDIR} @CPPFLAGS@
+# -I${MAGICDIR}: build top, for the generated database/database.h
+# -I${MAGICSRC}: source top, for "<module>/<header>.h" includes
+# -I${srcdir}:   this module's source dir, for same-directory headers
+CPPFLAGS               = -I${MAGICDIR} -I${MAGICSRC} -I${srcdir} @CPPFLAGS@
 CXXFLAGS               = @CXXFLAGS@
 DFLAGS_MAGICVERSION    = -DMAGIC_VERSION=\"${MAGIC_VERSION}\" -DMAGIC_REVISION=\"${MAGIC_REVISION}\" -DMAGIC_COMMIT=\"${MAGIC_COMMIT}\" "-DMAGIC_BUILDDATE=\"${MAGIC_BUILDDATE}\""
 DFLAGS                 = @extra_defs@ @stub_defs@ @DEFS@ ${DFLAGS_MAGICVERSION} -DGCORE=\"@GCORE@\"