diff --git a/build/autoconf/acoutput-fast.pl b/build/autoconf/acoutput-fast.pl
index 06f0668d5fe8ce1ca363a18457c29478bbb737f2..0e5e8761b569d8b37625c9088af18d636d228c55 100755
--- a/build/autoconf/acoutput-fast.pl
+++ b/build/autoconf/acoutput-fast.pl
@@ -132,7 +132,7 @@ foreach $ac_file (@makefiles) {
       $top_srcdir = $ac_dots;
       $top_srcdir =~ s%/$%%;
     }
-  } elsif ($ac_given_srcdir =~ m%^/%) {
+  } elsif ($ac_given_srcdir =~ m%^/% or $ac_given_srcdir =~ m%^.:/%) {
     $srcdir     = "$ac_given_srcdir$ac_dir_suffix";
     $top_srcdir = "$ac_given_srcdir";
   } else {
diff --git a/build/autoconf/make-makefile b/build/autoconf/make-makefile
index 069958a7239c832110272d90629492e4d5195638..03940d8920b762f79464fa0d404d1a2dd66310ec 100755
--- a/build/autoconf/make-makefile
+++ b/build/autoconf/make-makefile
@@ -208,7 +208,7 @@ sub update_makefiles {
         $top_srcdir = $ac_dots;
         $top_srcdir =~ s%/$%%;
       }
-    } elsif ($ac_given_srcdir =~ m%^/%) {
+    } elsif ($ac_given_srcdir =~ m%^/% or $ac_given_srcdir =~ m%^.:/%) {
       $srcdir     = "$ac_given_srcdir$ac_dir_suffix";
       $top_srcdir = "$ac_given_srcdir";
     } else {
@@ -246,14 +246,14 @@ sub update_makefiles {
     };
 
     while (<INFILE>) {
-      if (/\@[_a-zA-Z]*\@.*\@[_a-zA-Z]*\@/) {
-        #warn "Two defines on a line:$ac_file:$.:$_";
-        push @unhandled, $ac_file;
-        last;
-      }
-
-      s/\@srcdir\@/$srcdir/;
-      s/\@top_srcdir\@/$top_srcdir/;
+      #if (/\@[_a-zA-Z]*\@.*\@[_a-zA-Z]*\@/) {
+      #  #warn "Two defines on a line:$ac_file:$.:$_";
+      #  push @unhandled, $ac_file;
+      #  last;
+      #}
+
+      s/\@srcdir\@/$srcdir/g;
+      s/\@top_srcdir\@/$top_srcdir/g;
 
       if (/\@[_a-zA-Z]*\@/) {
         #warn "Unknown variable:$ac_file:$.:$_";
diff --git a/client.mk b/client.mk
index 5d35940617a54cee4a3302e40c18112297db08c2..c0f41a73b1040e29e78d8e3faa29265b5c1f91fc 100644
--- a/client.mk
+++ b/client.mk
@@ -78,8 +78,14 @@ ROOTDIR   := $(CWD)
 TOPSRCDIR := $(CWD)/mozilla
 endif
 
-ifeq "$(ROOTDIR)" "/"
-ROOTDIR   := /.
+# on os2, TOPSRCDIR may have two forward slashes in a row, which doesn't
+#  work;  replace first instance with one forward slash
+TOPSRCDIR := $(shell echo $(TOPSRCDIR) | sed s%//%/%)
+
+# if ROOTDIR equals only drive letter (i.e. "C:"), set to "/"
+DIRNAME := $(shell echo $(ROOTDIR) | sed s/^.://)
+ifeq ($(DIRNAME),)
+ROOTDIR := /.
 endif
 
 AUTOCONF := autoconf
@@ -109,6 +115,7 @@ endif
 
 CVSCO = $(strip cvs $(CVS_FLAGS) co $(CVS_CO_FLAGS))
 CVSCO_LOGFILE := $(ROOTDIR)/cvsco.log
+CVSCO_LOGFILE := $(shell echo $(CVSCO_LOGFILE) | sed s%//%/%)
 
 ifdef MOZ_CO_TAG
   CVS_CO_FLAGS :=  -r $(MOZ_CO_TAG)
diff --git a/config/rules.mk b/config/rules.mk
index 4194ad12c5d62749b6065fabcf0566b6c62e3769..fdf9af5a83fc65fa453a315fd557f8a9cefbe632 100644
--- a/config/rules.mk
+++ b/config/rules.mk
@@ -606,8 +606,8 @@ endif
 endif # BeOS
 ifeq ($(OS_ARCH),OS2)
 ifdef OS2_PROGRAM_RESOURCE
-	rc -n -x2 -r $(OS2_PROGRAM_RESOURCE)
-	rc -n -x2 $(patsubst %.rc,%.res,$(OS2_PROGRAM_RESOURCE)) $@
+	rc -n -x2 -i $(subst /,\,$(srcdir)) -r $(subst /,\,$(OS2_PROGRAM_RESOURCE)) $(patsubst %.rc, %.res, $(notdir $(OS2_PROGRAM_RESOURCE)))
+	rc -n -x2 -i $(subst /,\,$(srcdir)) $(patsubst %.rc, %.res, $(notdir $(OS2_PROGRAM_RESOURCE))) $@
 endif # os2_prog_rsrc
 endif
 
diff --git a/configure.in b/configure.in
index 655fce8c9c679997102d210f68f20b1486e39315..aaf7730b706e5c9aae6564b092cff5bbe61a272c 100644
--- a/configure.in
+++ b/configure.in
@@ -4347,11 +4347,9 @@ dnl Where the NSPR stuff gets installed: $DIST/{bin,lib,include}
 dnl 
 MOZ_NSPRENV_DIST=`pwd`/dist
 case "$target" in
-*-*-os2_emx)
-    MOZ_NSPRENV_DIST=`pwd -D`'/dist'
-    ;;
-*-*-os2_vacpp)
-    MOZ_NSPRENV_DIST="$ROOT"`pwd -D`'/dist'
+*-*-os2*)
+    MOZ_NSPRENV_DIST=`pwd -D | sed s/^.://`
+    MOZ_NSPRENV_DIST="$ROOT""$MOZ_NSPRENV_DIST/dist"
     ;;
 esac
 
diff --git a/uriloader/exthandler/Makefile.in b/uriloader/exthandler/Makefile.in
index 7f3bcba3ef3e6dd04ccfb45938eef3c1b28141ac..d5cf1df76cf254324ef7c985bc82e94a057a2733 100644
--- a/uriloader/exthandler/Makefile.in
+++ b/uriloader/exthandler/Makefile.in
@@ -41,11 +41,7 @@ else
 OSDIR	= unix
 endif
 
-ifeq ($(MOZ_OS2_TOOLS),VACPP)
-OSHELPER	= $(OSDIR)/nsOSHelperAppService.cpp
-else
 OSHELPER	= nsOSHelperAppService.cpp
-endif
 
 EXPORTS = 	nsExternalHelperAppService.h \
 		$(OSDIR)/nsOSHelperAppService.h \