diff --git a/gfx/2d/Matrix.cpp b/gfx/2d/Matrix.cpp
index b7bd9abb9ca..70058fede1e 100644
--- a/gfx/2d/Matrix.cpp
+++ b/gfx/2d/Matrix.cpp
@@ -6,6 +6,7 @@
 #include "Matrix.h"
 #include "Tools.h"
 #include <algorithm>
+#include <ostream>
 #include <math.h>
 
 #include "mozilla/FloatingPoint.h" // for UnspecifiedNaN
@@ -15,6 +16,18 @@ using namespace std;
 namespace mozilla {
 namespace gfx {
 
+std::ostream&
+operator<<(std::ostream& aStream, const Matrix& aMatrix)
+{
+  return aStream << "[ " << aMatrix._11
+                 << " "  << aMatrix._12
+                 << "; " << aMatrix._21
+                 << " "  << aMatrix._22
+                 << "; " << aMatrix._31
+                 << " "  << aMatrix._32
+                 << "; ]";
+}
+
 Matrix
 Matrix::Rotation(Float aAngle)
 {
diff --git a/gfx/2d/Matrix.h b/gfx/2d/Matrix.h
index c331dbb9c46..11dd2412b1b 100644
--- a/gfx/2d/Matrix.h
+++ b/gfx/2d/Matrix.h
@@ -9,6 +9,7 @@
 #include "Types.h"
 #include "Rect.h"
 #include "Point.h"
+#include <iosfwd>
 #include <math.h>
 #include "mozilla/Attributes.h"
 #include "mozilla/DebugOnly.h"
@@ -43,6 +44,8 @@ public:
     return Matrix(*this);
   }
 
+  friend std::ostream& operator<<(std::ostream& aStream, const Matrix& aMatrix);
+
   Point operator *(const Point &aPoint) const
   {
     Point retPoint;