diff --git a/modules/plugin/base/src/nsMalloc.h b/modules/plugin/base/src/nsMalloc.h
index a8a9f08ae4c..37ed149c74a 100644
--- a/modules/plugin/base/src/nsMalloc.h
+++ b/modules/plugin/base/src/nsMalloc.h
@@ -27,7 +27,7 @@
 #include "prmem.h"
 #include "nsAgg.h"
 
-class nsMalloc : nsIMalloc {
+class nsMalloc : public nsIMalloc {
 public:
 
     /**
diff --git a/modules/plugin/nglsrc/nsMalloc.h b/modules/plugin/nglsrc/nsMalloc.h
index a8a9f08ae4c..37ed149c74a 100644
--- a/modules/plugin/nglsrc/nsMalloc.h
+++ b/modules/plugin/nglsrc/nsMalloc.h
@@ -27,7 +27,7 @@
 #include "prmem.h"
 #include "nsAgg.h"
 
-class nsMalloc : nsIMalloc {
+class nsMalloc : public nsIMalloc {
 public:
 
     /**
diff --git a/modules/plugin/src/nsMalloc.h b/modules/plugin/src/nsMalloc.h
index a8a9f08ae4c..37ed149c74a 100644
--- a/modules/plugin/src/nsMalloc.h
+++ b/modules/plugin/src/nsMalloc.h
@@ -27,7 +27,7 @@
 #include "prmem.h"
 #include "nsAgg.h"
 
-class nsMalloc : nsIMalloc {
+class nsMalloc : public nsIMalloc {
 public:
 
     /**