diff --git a/iocBoot/iocNoAsyn/st.cmd b/iocBoot/iocNoAsyn/st.cmd
index 42b1fb7f..93a9c00c 100644
--- a/iocBoot/iocNoAsyn/st.cmd
+++ b/iocBoot/iocNoAsyn/st.cmd
@@ -10,6 +10,11 @@
 #< ../nfsCommands
 
 cd appbin
+
+# If the VxWorks kernel was built using the project facility, the following must
+# be added before any C++ code is loaded (see SPR #28980).
+sysCplusEnable=1
+
 ld < NoMPFLib
 
 cd startup
diff --git a/iocBoot/iocNoMPF/st.cmd b/iocBoot/iocNoMPF/st.cmd
index 42b1fb7f..93a9c00c 100644
--- a/iocBoot/iocNoMPF/st.cmd
+++ b/iocBoot/iocNoMPF/st.cmd
@@ -10,6 +10,11 @@
 #< ../nfsCommands
 
 cd appbin
+
+# If the VxWorks kernel was built using the project facility, the following must
+# be added before any C++ code is loaded (see SPR #28980).
+sysCplusEnable=1
+
 ld < NoMPFLib
 
 cd startup