diff --git a/security/nss/lib/pk11wrap/Makefile b/security/nss/lib/pk11wrap/Makefile
index efc60334f56..4810efd296f 100644
--- a/security/nss/lib/pk11wrap/Makefile
+++ b/security/nss/lib/pk11wrap/Makefile
@@ -75,10 +75,11 @@ include $(CORE_DEPTH)/coreconf/rules.mk
 export:: private_export
 
 # On AIX 4.3, IBM xlC_r compiler (version 3.6.6) cannot compile
-# pk11slot.c for unknown reasons.  A workaround is to compile it
-# with optimizations turned on.  (Bugzilla bug #63815)
+# pk11slot.c in 64-bit mode for unknown reasons.  A workaround is
+# to compile it with optimizations turned on.  (Bugzilla bug #63815)
 ifeq ($(OS_ARCH),AIX)
 ifeq ($(OS_RELEASE),4.3)
+ifeq ($(USE_64),1)
 ifndef BUILD_OPT
 $(OBJDIR)/pk11slot.o: pk11slot.c
 	@$(MAKE_OBJDIR)
@@ -86,3 +87,4 @@ $(OBJDIR)/pk11slot.o: pk11slot.c
 endif
 endif
 endif
+endif
diff --git a/security/nss/lib/softoken/Makefile b/security/nss/lib/softoken/Makefile
index ad4d0cc4d36..653bbb7abf7 100644
--- a/security/nss/lib/softoken/Makefile
+++ b/security/nss/lib/softoken/Makefile
@@ -74,4 +74,17 @@ include $(CORE_DEPTH)/coreconf/rules.mk
 
 export:: private_export
 
-
+# On AIX 4.3, IBM xlC_r compiler (version 3.6.6) cannot compile
+# pkcs11c.c in 64-bit mode for unknown reasons.  A workaround is
+# to compile it with optimizations turned on.  (Bugzilla bug #63815)
+ifeq ($(OS_ARCH),AIX)
+ifeq ($(OS_RELEASE),4.3)
+ifeq ($(USE_64),1)
+ifndef BUILD_OPT
+$(OBJDIR)/pkcs11c.o: pkcs11c.c
+	@$(MAKE_OBJDIR)
+	$(CC) -o $@ -c -O2 $(CFLAGS) $<
+endif
+endif
+endif
+endif