diff --git a/src/cas/build/Makefile b/src/cas/build/Makefile
index e5945e44e..ab4a14d99 100644
--- a/src/cas/build/Makefile
+++ b/src/cas/build/Makefile
@@ -73,6 +73,13 @@ LIBSRCS += casDGIntfIO.cc
 LIBSRCS += casStreamIO.cc
 LIBSRCS += ipIgnoreEntry.cc
 
+# There is a bug in some vxWorks compilers that these work around:
+ifeq ($(VX_GNU_VERSION), 4.1.2)
+  casStreamOS_CXXFLAGS_vxWorks-ppc604_altivec = -O0
+  casStreamOS_CXXFLAGS_vxWorks-ppc604_long = -O0
+  casStreamOS_CXXFLAGS_vxWorks-ppc604 = -O0
+endif
+
 LIBSRCS_vxWorks += templateInstances.cpp
 
 LIBRARY = cas