2 files changed, 9 insertions, 2 deletions
diff --git a/lib/sqlalchemy/databases/postgres.py b/lib/sqlalchemy/databases/postgres.py
index a9fa90c68..9f8e98607 100644
--- a/lib/sqlalchemy/databases/postgres.py
+++ b/lib/sqlalchemy/databases/postgres.py
@@ -631,6 +631,13 @@ class PGCompiler(compiler.DefaultCompiler):
         }
     )
 
+    functions = compiler.DefaultCompiler.functions.copy()
+    functions.update (
+        {
+            'TIMESTAMP':lambda x:'TIMESTAMP %s' % x,
+        }
+    )
+
     def visit_sequence(self, seq):
         if seq.optional:
             return None
diff --git a/lib/sqlalchemy/sql/compiler.py b/lib/sqlalchemy/sql/compiler.py
index c5ff974e5..8a2a5f2dd 100644
--- a/lib/sqlalchemy/sql/compiler.py
+++ b/lib/sqlalchemy/sql/compiler.py
@@ -349,7 +349,7 @@ class DefaultCompiler(engine.Compiled):
         name = self.function_string(func)
 
         if callable(name):
-            return name(*[self.process(x) for x in func.clause_expr])
+            return name(*[self.process(x) for x in func.clauses])
         else:
             return ".".join(func.packagenames + [name]) % {'expr':self.function_argspec(func)}
 
@@ -357,7 +357,7 @@ class DefaultCompiler(engine.Compiled):
         return self.process(func.clause_expr)
 
     def function_string(self, func):
-        return self.functions.get(func.__class__, func.name + "%(expr)s")
+        return self.functions.get(func.__class__, self.functions.get(func.name, func.name + "%(expr)s"))
 
     def visit_compound_select(self, cs, asfrom=False, parens=True, **kwargs):
         stack_entry = {'select':cs}