diff --git a/rbutil/libtools.make b/rbutil/libtools.make
index f9affdd9d4..dadc1a0545 100644
--- a/rbutil/libtools.make
+++ b/rbutil/libtools.make
@@ -75,6 +75,9 @@ ifeq ($(findstring APPLE,$(CPPDEFINES)),APPLE)
 # that to determine if we need to set arch and isysroot.
 ifeq ($(findstring __clang__,$(CPPDEFINES)),__clang__)
 GCCFLAGS += -mmacosx-version-min=10.5
+ifneq ($(ISYSROOT),)
+GCCFLAGS += -isysroot $(ISYSROOT)
+endif
 else
 # when building libs for OS X 10.4+ build for both i386 and ppc at the same time.
 # This creates fat objects, and ar can only create the archive but not operate
diff --git a/rbutil/rbutilqt/Makefile.libs b/rbutil/rbutilqt/Makefile.libs
index 938426f124..ac4e31a9e4 100644
--- a/rbutil/rbutilqt/Makefile.libs
+++ b/rbutil/rbutilqt/Makefile.libs
@@ -32,6 +32,7 @@ export CXXFLAGS=$(EXTRALIB_CXXFLAGS)
 export CC=$(EXTRALIBS_CC)
 export CXX=$(EXTRALIBS_CXX)
 export AR=$(EXTRALIBS_AR)
+export ISYSROOT=$(EXTRALIB_ISYSROOT)
 
 libs: librbspeex libucl libipodpatcher libsansapatcher libmkamsboot libmktccboot libmkmpioboot libchinachippatcher libmkimxboot libmks5lboot libbzip2 libbspatch librbtomcrypt
 
diff --git a/rbutil/rbutilqt/rbutilqt.pro b/rbutil/rbutilqt/rbutilqt.pro
index 9d7da92dbf..a7d0a179e6 100644
--- a/rbutil/rbutilqt/rbutilqt.pro
+++ b/rbutil/rbutilqt/rbutilqt.pro
@@ -35,6 +35,12 @@ EXTRALIBS_OPTS += EXTRALIBS_CC=\"$$QMAKE_CC\"
 EXTRALIBS_OPTS += EXTRALIBS_CXX=\"$$QMAKE_CXX\"
 EXTRALIBS_OPTS += EXTRALIB_CFLAGS=\"$$MACHINEFLAGS\"
 EXTRALIBS_OPTS += EXTRALIB_CXXFLAGS=\"$$MACHINEFLAGS\"
+macx {
+# on recent macOS we need to pass isysroot to the libs, otherwise it won't find
+# the standard libaries. This is caused by the passed compiler (doesn't rely on
+# default compiler but passed full path)
+    EXTRALIBS_OPTS += EXTRALIB_ISYSROOT=\"$$QMAKE_MAC_SDK.macosx.Path\"
+}
 
 MYBUILDDIR = $$OUT_PWD/build/
 MYLIBBUILDDIR = $$MYBUILDDIR/libs/
diff --git a/tools/rbspeex/Makefile b/tools/rbspeex/Makefile
index 231cdb5517..b33534695c 100644
--- a/tools/rbspeex/Makefile
+++ b/tools/rbspeex/Makefile
@@ -41,6 +41,9 @@ ifeq ($(findstring APPLE,$(CPPDEFINES)),APPLE)
 # that to determine if we need to set arch and isysroot.
 ifeq ($(findstring __clang__,$(CPPDEFINES)),__clang__)
 CFLAGS += -mmacosx-version-min=10.5
+ifneq ($(ISYSROOT),)
+CFLAGS += -isysroot $(ISYSROOT)
+endif
 else
 # when building libs for OS X 10.4+ build for both i386 and ppc at the same time.
 # This creates fat objects, and ar can only create the archive but not operate
diff --git a/tools/ucl/src/Makefile b/tools/ucl/src/Makefile
index a741f1ee8c..14ba2c2b04 100644
--- a/tools/ucl/src/Makefile
+++ b/tools/ucl/src/Makefile
@@ -36,6 +36,9 @@ ifeq ($(findstring APPLE,$(CPPDEFINES)),APPLE)
 # that to determine if we need to set arch and isysroot.
 ifeq ($(findstring __clang__,$(CPPDEFINES)),__clang__)
 CFLAGS += -mmacosx-version-min=10.5
+ifneq ($(ISYSROOT),)
+CFLAGS += -isysroot $(ISYSROOT)
+endif
 else
 # when building libs for OS X 10.4+ build for both i386 and ppc at the same time.
 # This creates fat objects, and ar can only create the archive but not operate
diff --git a/utils/tomcrypt/Makefile b/utils/tomcrypt/Makefile
index ce0f9bae47..4ca8c4e843 100644
--- a/utils/tomcrypt/Makefile
+++ b/utils/tomcrypt/Makefile
@@ -16,6 +16,10 @@ endif
 CFLAGS := -O3 -g -std=c99 -Wall $(DEFINES) -Isrc/headers
 LDFLAGS :=
 
+ifneq ($(ISYSROOT),)
+CFLAGS += -isysroot $(ISYSROOT)
+endif
+
 SOURCES := \
 	src/ciphers/aes/aes.c src/ciphers/aes/aes_tab.c \
 	src/misc/crypt/crypt_argchk.c src/misc/crypt/crypt_register_cipher.c src/misc/crypt/crypt_cipher_is_valid.c src/misc/crypt/crypt_cipher_descriptor.c \