diff --git a/cloudkitty/collector/prometheus.py b/cloudkitty/collector/prometheus.py
index e9d1db88..ee12b533 100644
--- a/cloudkitty/collector/prometheus.py
+++ b/cloudkitty/collector/prometheus.py
@@ -19,6 +19,7 @@ from decimal import ROUND_HALF_UP
 from oslo_config import cfg
 from oslo_log import log
 from voluptuous import In
+from voluptuous import Optional
 from voluptuous import Required
 from voluptuous import Schema
 
@@ -71,6 +72,12 @@ PROMETHEUS_EXTRA_SCHEMA = {
                 'min', 'stddev', 'stdvar',
                 'sum'
             ]),
+        Optional('query_function'):
+            In([
+                'abs', 'ceil', 'exp',
+                'floor', 'ln', 'log2',
+                'log10', 'round', 'sqrt'
+            ])
     }
 }
 
@@ -139,18 +146,40 @@ class PrometheusCollector(collector.BaseCollector):
         """Returns metrics to be valorized."""
         scope_key = CONF.collect.scope_key
         method = self.conf[metric_name]['extra_args']['aggregation_method']
+        query_function = self.conf[metric_name]['extra_args'].get(
+            'query_function')
         groupby = self.conf[metric_name].get('groupby', [])
         metadata = self.conf[metric_name].get('metadata', [])
         period = tzutils.diff_seconds(end, start)
         time = end
 
-        query = '{0}({0}_over_time({1}{{{2}="{3}"}}[{4}s])) by ({5})'.format(
-            method,
+        # The metric with the period
+        query = '{0}{{{1}="{2}"}}[{3}s]'.format(
             metric_name,
             scope_key,
             scope_id,
-            period,
-            ', '.join(groupby + metadata),
+            period
+        )
+        # Applying the aggregation_method on a Range Vector
+        query = "{0}_over_time({1})".format(
+            method,
+            query
+        )
+        # Applying the query_function
+        if query_function is not None:
+            query = "{0}({1})".format(
+                query_function,
+                query
+            )
+        # Applying the aggregation_method on a Instant Vector
+        query = "{0}({1})".format(
+            method,
+            query
+        )
+        # Filter by groupby and metadata
+        query = "{0} by ({1})".format(
+            query,
+            ', '.join(groupby + metadata)
         )
 
         try:
diff --git a/cloudkitty/tests/collectors/test_prometheus.py b/cloudkitty/tests/collectors/test_prometheus.py
index 07c0ce9b..ddc03047 100644
--- a/cloudkitty/tests/collectors/test_prometheus.py
+++ b/cloudkitty/tests/collectors/test_prometheus.py
@@ -47,6 +47,7 @@ class PrometheusCollectorTest(tests.TestCase):
                         ],
                         'extra_args': {
                             'aggregation_method': 'avg',
+                            'query_function': 'abs'
                         },
                     },
                 }
@@ -56,9 +57,9 @@ class PrometheusCollectorTest(tests.TestCase):
 
     def test_fetch_all_build_query(self):
         query = (
-            'avg(avg_over_time(http_requests_total'
+            'avg(abs(avg_over_time(http_requests_total'
             '{project_id="f266f30b11f246b589fd266f85eeec39"}[3600s]'
-            ')) by (foo, bar, project_id, code, instance)'
+            '))) by (foo, bar, project_id, code, instance)'
         )
 
         with mock.patch.object(
diff --git a/cloudkitty/tests/collectors/test_validation.py b/cloudkitty/tests/collectors/test_validation.py
index 7b2cc5d6..5e0a235f 100644
--- a/cloudkitty/tests/collectors/test_validation.py
+++ b/cloudkitty/tests/collectors/test_validation.py
@@ -156,11 +156,13 @@ class MetricConfigValidationTest(tests.TestCase):
         data = copy.deepcopy(self.base_data)
         data['metrics']['metric_one']['extra_args'] = {
             'aggregation_method': 'max',
+            'query_function': 'abs',
         }
         expected_output = copy.deepcopy(self.base_output)
         expected_output['metric_one']['groupby'].append('project_id')
         expected_output['metric_one']['extra_args'] = {
             'aggregation_method': 'max',
+            'query_function': 'abs',
         }
 
         self.assertEqual(
diff --git a/doc/source/admin/configuration/collector.rst b/doc/source/admin/configuration/collector.rst
index b689f945..25b65c30 100644
--- a/doc/source/admin/configuration/collector.rst
+++ b/doc/source/admin/configuration/collector.rst
@@ -302,3 +302,11 @@ Prometheus
 * ``aggregation_method``: Defaults to ``max``. The aggregation method to use
   when retrieving measures from prometheus. Must be one of ``avg``, ``min``,
   ``max``, ``sum``, ``count``, ``stddev``, ``stdvar``.
+
+* ``query_function``: Optional argument. The function to apply to an instant
+  vector after the ``aggregation_method`` or ``range_function`` has altered the
+  data. Must be one of ``abs``, ``ceil``, ``exp``, ``floor``, ``ln``, ``log2``,
+  ``log10``, ``round``, ``sqrt``. For more information on these functions,
+  you can check `this page`_
+
+.. _this page: https://prometheus.io/docs/prometheus/latest/querying/basics/