diff --git a/dom/canvas/WebGL2Context.h b/dom/canvas/WebGL2Context.h
index 34a7a016da0d..23b6eeaa0c3b 100644
--- a/dom/canvas/WebGL2Context.h
+++ b/dom/canvas/WebGL2Context.h
@@ -248,6 +248,7 @@ private:
     bool ValidateTexStorage(GLenum target, GLsizei levels, GLenum internalformat,
                                 GLsizei width, GLsizei height, GLsizei depth,
                                 const char* info);
+    JS::Value GetTexParameterInternal(const TexTarget& target, GLenum pname) MOZ_OVERRIDE;
 };
 
 } // namespace mozilla
diff --git a/dom/canvas/WebGL2ContextTextures.cpp b/dom/canvas/WebGL2ContextTextures.cpp
index 3cef3736d708..637837e372aa 100644
--- a/dom/canvas/WebGL2ContextTextures.cpp
+++ b/dom/canvas/WebGL2ContextTextures.cpp
@@ -345,3 +345,17 @@ WebGL2Context::CompressedTexSubImage3D(GLenum target, GLint level, GLint xoffset
 {
     MOZ_CRASH("Not Implemented.");
 }
+
+JS::Value
+WebGL2Context::GetTexParameterInternal(const TexTarget& target, GLenum pname)
+{
+    switch (pname) {
+        case LOCAL_GL_TEXTURE_IMMUTABLE_FORMAT:
+        {
+            GLint i = 0;
+            gl->fGetTexParameteriv(target.get(), pname, &i);
+            return JS::NumberValue(uint32_t(i));
+        }
+    }
+    return WebGLContext::GetTexParameterInternal(target, pname);
+}
diff --git a/dom/canvas/WebGLContext.h b/dom/canvas/WebGLContext.h
index dd528176b27a..6a10cfe38c2f 100644
--- a/dom/canvas/WebGLContext.h
+++ b/dom/canvas/WebGLContext.h
@@ -990,6 +990,8 @@ protected:
                                       uint32_t pixelSize,
                                       uint32_t alignment);
 
+    virtual JS::Value GetTexParameterInternal(const TexTarget& target, GLenum pname);
+
     // Returns x rounded to the next highest multiple of y.
     static CheckedUint32 RoundedToNextMultipleOf(CheckedUint32 x, CheckedUint32 y) {
         return ((x + y - 1) / y) * y;
diff --git a/dom/canvas/WebGLContextGL.cpp b/dom/canvas/WebGLContextGL.cpp
index 8608deeaa528..ad5143caa4de 100644
--- a/dom/canvas/WebGLContextGL.cpp
+++ b/dom/canvas/WebGLContextGL.cpp
@@ -1611,6 +1611,12 @@ WebGLContext::GetTexParameter(GLenum rawTarget, GLenum pname)
         return JS::NullValue();
     }
 
+    return GetTexParameterInternal(target, pname);
+}
+
+JS::Value
+WebGLContext::GetTexParameterInternal(const TexTarget& target, GLenum pname)
+{
     switch (pname) {
         case LOCAL_GL_TEXTURE_MIN_FILTER:
         case LOCAL_GL_TEXTURE_MAG_FILTER: