diff --git a/mozilla/xpcom/base/nsDebug.cpp b/mozilla/xpcom/base/nsDebug.cpp
index 7f30255cab8..76408c92c02 100644
--- a/mozilla/xpcom/base/nsDebug.cpp
+++ b/mozilla/xpcom/base/nsDebug.cpp
@@ -339,6 +339,8 @@ NS_ErrorAccordingToNSPR()
 #include "nsISupportsUtils.h"
 #include "prthread.h"
 
+extern "C" NS_EXPORT void* NS_CurrentThread(void);
+
 void*
 NS_CurrentThread(void)
 {
diff --git a/mozilla/xpcom/build/dlldeps.cpp b/mozilla/xpcom/build/dlldeps.cpp
index 19c67a93975..48e05c4d146 100644
--- a/mozilla/xpcom/build/dlldeps.cpp
+++ b/mozilla/xpcom/build/dlldeps.cpp
@@ -61,6 +61,7 @@
 #include "nsIInterfaceRequestor.h"
 #ifdef DEBUG
 #include "pure.h"
+extern "C" NS_EXPORT void* NS_CurrentThread(void);
 #endif
 
 class dummyComparitor: public nsAVLNodeComparitor {
diff --git a/mozilla/xpcom/glue/nsDebug.cpp b/mozilla/xpcom/glue/nsDebug.cpp
index 7f30255cab8..76408c92c02 100644
--- a/mozilla/xpcom/glue/nsDebug.cpp
+++ b/mozilla/xpcom/glue/nsDebug.cpp
@@ -339,6 +339,8 @@ NS_ErrorAccordingToNSPR()
 #include "nsISupportsUtils.h"
 #include "prthread.h"
 
+extern "C" NS_EXPORT void* NS_CurrentThread(void);
+
 void*
 NS_CurrentThread(void)
 {