diff --git a/IPython/nbconvert/exporters/latex.py b/IPython/nbconvert/exporters/latex.py
index 13015c3..779a8cc 100644
--- a/IPython/nbconvert/exporters/latex.py
+++ b/IPython/nbconvert/exporters/latex.py
@@ -37,7 +37,7 @@ class LatexExporter(TemplateExporter):
     """
 
     def _file_extension_default(self):
-        return 'tex'
+        return '.tex'
 
     def _template_file_default(self):
         return 'article'
diff --git a/IPython/nbconvert/exporters/slides.py b/IPython/nbconvert/exporters/slides.py
index 8f4545e..fa84248 100644
--- a/IPython/nbconvert/exporters/slides.py
+++ b/IPython/nbconvert/exporters/slides.py
@@ -25,7 +25,7 @@ class SlidesExporter(HTMLExporter):
     """Exports HTML slides with reveal.js"""
     
     def _file_extension_default(self):
-        return 'slides.html'
+        return '.slides.html'
 
     def _template_file_default(self):
         return 'slides_reveal'