diff --git a/master.cfg b/master.cfg
--- a/master.cfg
+++ b/master.cfg
@@ -1293,23 +1293,18 @@ class RunTestGDBSolaris_Common (BuildAnd
         # build/23676.  This can be avoided either by performing a -g
         # -O build or with --disable-unit-tests from Sergio's proposed
         # patch.
-        self.disable_default_compilation_flags = True
+        self.extra_CFLAGS = [ '-O' ]
+        self.extra_CXXFLAGS = self.extra_CFLAGS
         BuildAndTestGDBFactory.__init__ (self, **kwargs)
 
 class RunTestGDBPlainSolaris_c64 (RunTestGDBSolaris_Common):
     """Compiling for Solaris"""
     def __init__ (self, **kwargs):
-        self.extra_CFLAGS = [ '-m64' ]
-        self.extra_CXXFLAGS = self.extra_CFLAGS
         self.enable_targets_all = False
         self.make_command = 'gmake'
         self.run_testsuite = False
-        # While a regular gdb build succeeds, a -g -D_GLIBCXX_DEBUG
-        # build as used by the buildbot fails as reported in PR
-        # build/23676.  This can be avoided either by performing a -g
-        # -O build or with --disable-unit-tests from Sergio's proposed
-        # patch.
-        self.disable_default_compilation_flags = True
+        self.extra_CFLAGS.append ('-m64')
+        self.extra_CXXFLAGS.append ('-m64')
         BuildAndTestGDBFactory.__init__ (self, **kwargs)
 
 # All branches that are going to be watched.