diff --git a/harbour/ChangeLog b/harbour/ChangeLog
index 547bf393df..840030d062 100644
--- a/harbour/ChangeLog
+++ b/harbour/ChangeLog
@@ -16,6 +16,29 @@
    The license applies to all entries newer than 2009-04-28.
 */
 
+2010-06-15 18:43 UTC+0200 Viktor Szakats (harbour.01 syenar.hu)
+  * INSTALL
+  * config/global.mk
+  * config/detfun.mk
+  * config/detect.mk
+  * external/sqlite3/Makefile
+  * external/png/Makefile
+  * external/jpeg/Makefile
+  * external/bzip2/Makefile
+  * external/libhpdf/Makefile
+  * contrib/hbsqlit3/Makefile
+  * contrib/hbmzip/Makefile
+  * contrib/hbbz2/Makefile
+  * contrib/hbhpdf/Makefile
+  * contrib/sddsqlt3/Makefile
+  * contrib/hbwin/Makefile
+    + Added HB_ROOT variable which can be used to specify Harbour
+      source tree root as an absolute directory, when using
+      older than 3.81 GNU Make version (f.e. on QNX).
+    + Changed the way locally hosted source directories are
+      specified for detection function, in order to support
+      HB_ROOT functionality.
+
 2010-06-15 18:06 UTC+0200 Viktor Szakats (harbour.01 syenar.hu)
   * INSTALL
     + Added Mac OS X QT pkg recommended link.
diff --git a/harbour/INSTALL b/harbour/INSTALL
index 38d93e55ce..fec321fdd7 100644
--- a/harbour/INSTALL
+++ b/harbour/INSTALL
@@ -667,6 +667,12 @@ HARBOUR
                                  Lib names should be without extension and path.
                                  You only need this in special cases, like CodeGuard
                                  build with bcc.
+   - HB_ROOT=<dir>               When using GNU Make older than 3.81, you shall set
+                                 the root directory of Harbour source tree as an
+                                 absolute path. If not set, some build functionality
+                                 may fail, like detection of 3rd party libraries with
+                                 locally hosted sources.
+                                 With newer make versions, this variable is ignored.
    - HB_REBUILD_PARSER=yes       Rebuild language parser sources. Typically
                                  you only need this if your are Harbour core
                                  developer modifying grammar rules (.y).
@@ -1407,7 +1413,7 @@ HARBOUR
       HB_WITH_QT - Nokia QT (GUI) [win, wce, os2, darwin, linux, free, open-source]
          http://qt.nokia.com/products/
          http://get.qt.nokia.com/qt/source/
-         Recommended OS X binary package:
+         Recommended Mac OS X binary package:
             http://get.qt.nokia.com/qt/source/qt-mac-cocoa-opensource-4.6.3.dmg
          Currently supported Windows binary package:
             http://get.qt.nokia.com/qt/source/qt-win-opensource-4.5.3-mingw.exe
diff --git a/harbour/config/detect.mk b/harbour/config/detect.mk
index 5a910ac812..7efaf88e3a 100644
--- a/harbour/config/detect.mk
+++ b/harbour/config/detect.mk
@@ -48,7 +48,7 @@ _DET_VAR_HAS_ := HB_HAS_ZLIB
 _DET_FLT_PLAT :=
 _DET_FLT_COMP :=
 _DET_INC_DEFP := /usr/include /usr/local/include /boot/develop/headers/3rdparty
-_DET_INC_LOCL := $(realpath $(TOP)$(ROOT)external/zlib)
+_DET_INC_LOCL := external/zlib
 _DET_INC_HEAD := /zlib.h
 
 include $(TOP)$(ROOT)config/detfun.mk
@@ -61,7 +61,7 @@ _DET_VAR_HAS_ := HB_HAS_PCRE
 _DET_FLT_PLAT :=
 _DET_FLT_COMP :=
 _DET_INC_DEFP := /usr/include /usr/local/include /usr/pkg/include /opt/local/include
-_DET_INC_LOCL := $(realpath $(TOP)$(ROOT)external/pcre)
+_DET_INC_LOCL := external/pcre
 _DET_INC_HEAD := /pcre.h
 
 include $(TOP)$(ROOT)config/detfun.mk
diff --git a/harbour/config/detfun.mk b/harbour/config/detfun.mk
index e2bb00281a..cade14fe65 100644
--- a/harbour/config/detfun.mk
+++ b/harbour/config/detfun.mk
@@ -20,7 +20,7 @@
 #       _DET_INC_DEFP - default location to look at. Not effective in 'HB_BUILD_EXTDEF=no' mode.
 #                       (you must use absolute paths only.)
 #       _DET_INC_LOCL - embedded location to look at.
-#                       (you must use absolute paths only.)
+#                       (you must use paths relative to Harbour source tree root.)
 #       _DET_INC_HEAD - header filename to look for. Unless looking for a directory, prefix with forward slash.
 #       - variable name specified by _DET_VAR_INC_ (typically "HB_WITH_*") containing:
 #          (empty) or yes - will enable external component if found on default locations.
@@ -53,6 +53,12 @@ ifneq ($($(subst HB_INC_,HB_WITH_,$(_DET_VAR_INC_))),)
    $(_DET_VAR_INC_) := $($(subst HB_INC_,HB_WITH_,$(_DET_VAR_INC_)))
 endif
 
+ifneq ($(HB_ROOT),)
+   _DET_INC_LOCL := $(HB_ROOT)/$(_DET_INC_LOCL)
+else
+   _DET_INC_LOCL := $(realpath $(TOP)$(ROOT)$(_DET_INC_LOCL))
+endif
+
 _DET_RES_TEXT :=
 
 ifeq ($($(_DET_VAR_HAS_)),)
diff --git a/harbour/config/global.mk b/harbour/config/global.mk
index bbcfdd74c2..c43c6b3219 100644
--- a/harbour/config/global.mk
+++ b/harbour/config/global.mk
@@ -63,6 +63,15 @@ endif
 _make_ver_381 := 3.81
 MAKE_381 := $(filter $(_make_ver_381),$(firstword $(sort $(MAKE_VERSION) $(_make_ver_381))))
 
+# Users must specify HB_ROOT only for pre-3.81 GNU Make versions
+# (without '$(realpath)' function). For newer ones we clear it
+# to avoid messing things up.
+ifneq ($(MAKE_381),)
+   HB_ROOT :=
+else
+   HB_ROOT := $(subst \,/,$(HB_ROOT))
+endif
+
 find_in_path     = $(strip $(subst $(substpat), ,$(firstword $(subst |, ,$(subst $(subst x, ,x),$(substpat),$(filter-out |,$(foreach dir, $(subst $(PTHSEP), ,$(subst $(subst x, ,x),$(substpat),$(PATH))),|$(wildcard $(subst //,/,$(subst $(substpat),\ ,$(subst \,/,$(dir)))/$(1))$(HB_HOST_BIN_EXT)))))))))
 find_in_path_raw = $(strip $(subst $(substpat), ,$(firstword $(subst |, ,$(subst $(subst x, ,x),$(substpat),$(filter-out |,$(foreach dir, $(subst $(PTHSEP), ,$(subst $(subst x, ,x),$(substpat),$(PATH))),|$(wildcard $(subst //,/,$(subst $(substpat),\ ,$(subst \,/,$(dir)))/$(1))))))))))
 find_in_path_par = $(strip $(subst $(substpat), ,$(firstword $(subst |, ,$(subst $(subst x, ,x),$(substpat),$(filter-out |,$(foreach dir, $(subst $(PTHSEP), ,$(subst $(subst x, ,x),$(substpat),$(2))),|$(wildcard $(subst //,/,$(subst $(substpat),\ ,$(subst \,/,$(dir)))/$(1))$(HB_HOST_BIN_EXT)))))))))
@@ -1489,7 +1498,11 @@ else
          HB_INSTALL_PREFIX := /boot/common
       else
       ifeq ($(HB_PLATFORM_UNIX),)
-         HB_INSTALL_PREFIX := $(realpath $(TOP)$(ROOT))
+         ifneq ($(HB_ROOT),)
+            HB_INSTALL_PREFIX := $(HB_ROOT)$(TOP)$(ROOT)
+         else
+            HB_INSTALL_PREFIX := $(realpath $(TOP)$(ROOT))
+         endif
       else
       ifneq ($(PREFIX),)
          HB_INSTALL_PREFIX := $(PREFIX)
diff --git a/harbour/contrib/hbbz2/Makefile b/harbour/contrib/hbbz2/Makefile
index 3069586b91..5dfc95f9bf 100644
--- a/harbour/contrib/hbbz2/Makefile
+++ b/harbour/contrib/hbbz2/Makefile
@@ -20,7 +20,7 @@ _DET_VAR_HAS_ := HB_HAS_BZIP2
 _DET_FLT_PLAT := !wce
 _DET_FLT_COMP :=
 _DET_INC_DEFP := /usr/include
-_DET_INC_LOCL := $(realpath $(TOP)$(ROOT)external/bzip2)
+_DET_INC_LOCL := external/bzip2
 _DET_INC_HEAD := /bzlib.h
 include $(TOP)$(ROOT)config/detfun.mk
 
diff --git a/harbour/contrib/hbhpdf/Makefile b/harbour/contrib/hbhpdf/Makefile
index 1e4a7a1fd8..cf23917b73 100644
--- a/harbour/contrib/hbhpdf/Makefile
+++ b/harbour/contrib/hbhpdf/Makefile
@@ -20,7 +20,7 @@ _DET_VAR_HAS_ := HB_HAS_LIBHARU
 _DET_FLT_PLAT :=
 _DET_FLT_COMP :=
 _DET_INC_DEFP := /usr/include /usr/local/include
-_DET_INC_LOCL := $(realpath $(TOP)$(ROOT)external/libhpdf)
+_DET_INC_LOCL := external/libhpdf
 _DET_INC_HEAD := /hpdf.h
 include $(TOP)$(ROOT)config/detfun.mk
 
diff --git a/harbour/contrib/hbmzip/Makefile b/harbour/contrib/hbmzip/Makefile
index ea07eafe60..cf701eb8f8 100644
--- a/harbour/contrib/hbmzip/Makefile
+++ b/harbour/contrib/hbmzip/Makefile
@@ -24,7 +24,7 @@ ifneq ($(HB_HAS_ZLIB),)
    _DET_FLT_PLAT :=
    _DET_FLT_COMP :=
    _DET_INC_DEFP := /usr/include /usr/local/include
-   _DET_INC_LOCL := $(realpath $(TOP)$(ROOT)external/minizip)
+   _DET_INC_LOCL := external/minizip
    _DET_INC_HEAD := /zip.h
    include $(TOP)$(ROOT)config/detfun.mk
 
diff --git a/harbour/contrib/hbsqlit3/Makefile b/harbour/contrib/hbsqlit3/Makefile
index c0e8794eab..f8e0e65564 100644
--- a/harbour/contrib/hbsqlit3/Makefile
+++ b/harbour/contrib/hbsqlit3/Makefile
@@ -20,7 +20,7 @@ _DET_VAR_HAS_ := HB_HAS_SQLITE3
 _DET_FLT_PLAT :=
 _DET_FLT_COMP :=
 _DET_INC_DEFP := /usr/include /boot/common/include
-_DET_INC_LOCL := $(realpath $(TOP)$(ROOT)external/sqlite3)
+_DET_INC_LOCL := external/sqlite3
 _DET_INC_HEAD := /sqlite3.h
 include $(TOP)$(ROOT)config/detfun.mk
 
diff --git a/harbour/contrib/hbwin/Makefile b/harbour/contrib/hbwin/Makefile
index 1908fe1398..2d201eee5d 100644
--- a/harbour/contrib/hbwin/Makefile
+++ b/harbour/contrib/hbwin/Makefile
@@ -71,7 +71,7 @@ ifneq ($(filter $(HB_PLATFORM),win wce),)
    _DET_FLT_PLAT :=
    _DET_FLT_COMP :=
    _DET_INC_DEFP :=
-   _DET_INC_LOCL := $(realpath $(TOP)$(ROOT)external/libpng)
+   _DET_INC_LOCL := external/libpng
    _DET_INC_HEAD := /png.h
    include $(TOP)$(ROOT)config/detfun.mk
 
diff --git a/harbour/contrib/sddsqlt3/Makefile b/harbour/contrib/sddsqlt3/Makefile
index 0ccc90c15c..bb07eb3626 100644
--- a/harbour/contrib/sddsqlt3/Makefile
+++ b/harbour/contrib/sddsqlt3/Makefile
@@ -17,7 +17,7 @@ _DET_VAR_HAS_ := HB_HAS_SQLITE3
 _DET_FLT_PLAT :=
 _DET_FLT_COMP :=
 _DET_INC_DEFP := /usr/include /boot/common/include
-_DET_INC_LOCL := $(realpath $(TOP)$(ROOT)external/sqlite3)
+_DET_INC_LOCL := external/sqlite3
 _DET_INC_HEAD := /sqlite3.h
 include $(TOP)$(ROOT)config/detfun.mk
 
diff --git a/harbour/external/bzip2/Makefile b/harbour/external/bzip2/Makefile
index 2de39fc2c1..739b4b2908 100644
--- a/harbour/external/bzip2/Makefile
+++ b/harbour/external/bzip2/Makefile
@@ -26,7 +26,7 @@ _DET_VAR_HAS_ := HB_HAS_BZIP2
 _DET_FLT_PLAT := !wce
 _DET_FLT_COMP :=
 _DET_INC_DEFP := /usr/include
-_DET_INC_LOCL := $(realpath $(TOP)$(ROOT)external/bzip2)
+_DET_INC_LOCL := external/bzip2
 _DET_INC_HEAD := /bzlib.h
 include $(TOP)$(ROOT)config/detfun.mk
 
diff --git a/harbour/external/jpeg/Makefile b/harbour/external/jpeg/Makefile
index 66a4eba3e3..1c43e1d10f 100644
--- a/harbour/external/jpeg/Makefile
+++ b/harbour/external/jpeg/Makefile
@@ -84,7 +84,7 @@ ifeq ($(filter $(HB_COMPILER),<>),)
    _DET_FLT_PLAT :=
    _DET_FLT_COMP :=
    _DET_INC_DEFP := /usr/include
-   _DET_INC_LOCL := $(realpath $(TOP)$(ROOT)external/jpeg)
+   _DET_INC_LOCL := external/jpeg
    _DET_INC_HEAD := /jpeglib.h
    include $(TOP)$(ROOT)config/detfun.mk
 
diff --git a/harbour/external/libhpdf/Makefile b/harbour/external/libhpdf/Makefile
index 76855cc7c5..03b82da364 100644
--- a/harbour/external/libhpdf/Makefile
+++ b/harbour/external/libhpdf/Makefile
@@ -88,7 +88,7 @@ ifeq ($(HB_SUPPORTED),yes)
    _DET_FLT_PLAT :=
    _DET_FLT_COMP :=
    _DET_INC_DEFP := /usr/include /usr/local/include
-   _DET_INC_LOCL := $(realpath $(TOP)$(ROOT)external/libhpdf)
+   _DET_INC_LOCL := external/libhpdf
    _DET_INC_HEAD := /hpdf.h
    include $(TOP)$(ROOT)config/detfun.mk
 
@@ -100,7 +100,7 @@ ifeq ($(HB_SUPPORTED),yes)
       _DET_FLT_PLAT :=
       _DET_FLT_COMP :=
       _DET_INC_DEFP := /usr/include /opt/local/include
-      _DET_INC_LOCL := $(realpath $(TOP)$(ROOT)external/png)
+      _DET_INC_LOCL := external/png
       _DET_INC_HEAD := /png.h
       include $(TOP)$(ROOT)config/detfun.mk
 
diff --git a/harbour/external/png/Makefile b/harbour/external/png/Makefile
index 5b69fde916..2accee7942 100644
--- a/harbour/external/png/Makefile
+++ b/harbour/external/png/Makefile
@@ -36,7 +36,7 @@ ifeq ($(filter $(HB_COMPILER),poccarm xcc),)
    _DET_FLT_PLAT :=
    _DET_FLT_COMP :=
    _DET_INC_DEFP := /usr/include /boot/develop/headers/3rdparty
-   _DET_INC_LOCL := $(realpath $(TOP)$(ROOT)external/png)
+   _DET_INC_LOCL := external/png
    _DET_INC_HEAD := /png.h
    include $(TOP)$(ROOT)config/detfun.mk
 
diff --git a/harbour/external/sqlite3/Makefile b/harbour/external/sqlite3/Makefile
index 4eb2a7cb30..5a0e8b7dff 100644
--- a/harbour/external/sqlite3/Makefile
+++ b/harbour/external/sqlite3/Makefile
@@ -44,7 +44,7 @@ ifeq ($(HB_SUPPORTED),yes)
    _DET_FLT_PLAT :=
    _DET_FLT_COMP :=
    _DET_INC_DEFP := /usr/include
-   _DET_INC_LOCL := $(realpath $(TOP)$(ROOT)external/sqlite3)
+   _DET_INC_LOCL := external/sqlite3
    _DET_INC_HEAD := /sqlite3.h
    include $(TOP)$(ROOT)config/detfun.mk