diff --git a/master.cfg b/master.cfg
index 5a47fb5..fb76cbe 100644
--- a/master.cfg
+++ b/master.cfg
@@ -817,7 +817,7 @@ class RunTestGDBPlain_c64t64 (BuildAndTestGDBFactory):
 class RunTestGDBPlain_c32t32 (BuildAndTestGDBFactory):
     """Compiling on 32-bit, testing on 32-bit."""
     def __init__ (self, **kwargs):
-        self.extra_conf_flags = [ r'CFLAGS=-m32' ]
+        self.extra_conf_flags = [ r'CFLAGS=-m32', 'CXXFLAGS=-m32' ]
         self.extra_make_check_flags = [ r'RUNTESTFLAGS=--target_board unix/-m32' ]
         BuildAndTestGDBFactory.__init__ (self, **kwargs)
 
@@ -842,7 +842,7 @@ class RunTestGDBNativeGDBServer_c64t32 (BuildAndTestGDBFactory):
 class RunTestGDBNativeGDBServer_c32t32 (BuildAndTestGDBFactory):
     """Compiling on 32-bit, testing native-gdbserver on 32-bit."""
     def __init__ (self, **kwargs):
-        self.extra_conf_flags = [ 'CFLAGS=-m32']
+        self.extra_conf_flags = [ 'CFLAGS=-m32', 'CXXFLAGS=-m32' ]
         self.extra_make_check_flags = [ 'RUNTESTFLAGS=--target_board native-gdbserver/-m32']
         BuildAndTestGDBFactory.__init__ (self, **kwargs)
 
@@ -861,7 +861,7 @@ class RunTestGDBNativeExtendedGDBServer_c64t32 (BuildAndTestGDBFactory):
 class RunTestGDBNativeExtendedGDBServer_c32t32 (BuildAndTestGDBFactory):
     """Compiling on 64-bit, testing native-extended-gdbserver on 32-bit."""
     def __init__ (self, **kwargs):
-        self.extra_conf_flags = [ 'CFLAGS=-m32']
+        self.extra_conf_flags = [ 'CFLAGS=-m32', 'CXXFLAGS=-m32' ]
         self.extra_make_check_flags = [ r'RUNTESTFLAGS=--target_board native-extended-gdbserver/-m32' ]
         BuildAndTestGDBFactory.__init__ (self, **kwargs)
 
@@ -875,7 +875,7 @@ class RunTestGDBIndexBuild (BuildAndTestGDBFactory):
 class RunTestGDBIndexBuild_c32t32 (BuildAndTestGDBFactory):
     """Testing with the "cc-with-tweaks.sh" passing -i.  32-bit version"""
     def __init__ (self, **kwargs):
-        self.extra_conf_flags = [ 'CFLAGS=-m32' ]
+        self.extra_conf_flags = [ 'CFLAGS=-m32', 'CXXFLAGS=-m32' ]
         self.extra_make_check_flags = [ WithProperties (r'CC_FOR_TARGET=/bin/sh %s/binutils-gdb/gdb/contrib/cc-with-tweaks.sh -i gcc', r'builddir'),
                                         WithProperties (r'CXX_FOR_TARGET=/bin/sh %s/binutils-gdb/gdb/contrib/cc-with-tweaks.sh -i g++', r'builddir'),
                                         'RUNTESTFLAGS=--target_board unix/-m32' ]