diff --git a/python/plugins/processing/algs/grass7/description/r.colors.txt b/python/plugins/processing/algs/grass7/description/r.colors.txt
index 6651e95ea0b..a4bdf2702d7 100644
--- a/python/plugins/processing/algs/grass7/description/r.colors.txt
+++ b/python/plugins/processing/algs/grass7/description/r.colors.txt
@@ -4,7 +4,7 @@ Raster (r.*)
 ParameterMultipleInput|map|Name of raster maps(s)|3|False
 ParameterSelection|color|Name of color table|not selected;aspect;aspectcolr;bcyr;bgyr;blues;byg;byr;celsius;corine;curvature;differences;elevation;etopo2;evi;fahrenheit;gdd;greens;grey;grey.eq;grey.log;grey1.0;grey255;gyr;haxby;kelvin;ndvi;ndwi;oranges;population;population_dens;precipitation;precipitation_daily;precipitation_monthly;rainbow;ramp;random;reds;rstcurv;ryb;ryg;sepia;slope;srtm;srtm_plus;terrain;wave|0|False|True
 ParameterString|rules_txt|Color rules|None|True|True
-ParameterFile|rules|Color rules file|True
+ParameterFile|rules|Color rules file|False|True
 ParameterRaster|raster|Raster map from which to copy color table|True
 ParameterBoolean|-r|Remove existing color table|False
 ParameterBoolean|-w|Only write new color table if it does not already exist|False
diff --git a/python/plugins/processing/algs/grass7/ext/r_colors.py b/python/plugins/processing/algs/grass7/ext/r_colors.py
index 8a750b2220e..d8ddfa1789c 100644
--- a/python/plugins/processing/algs/grass7/ext/r_colors.py
+++ b/python/plugins/processing/algs/grass7/ext/r_colors.py
@@ -30,7 +30,7 @@ import os
 
 def checkParameterValuesBeforeExecuting(alg):
     """ Verify if we have the right parameters """
-    if alg.getParameterValue(u'rules_txt') and alg.getParameterValue(u'rules'):
+    if alg.getParameterValue('rules_txt') and alg.getParameterValue('rules'):
         return alg.tr("You need to set either inline rules or a rules file !")
 
     return None
@@ -79,11 +79,26 @@ def processCommand(alg):
     if color.value == 0:
         alg.parameters.remove(color)
 
-    # TODO Handle rules
+    # Handle rules
+    txtRules = alg.getParameterFromName('rules_txt')
+    if txtRules.value:
+        # Creates a temporary txt file
+        tempRulesName = alg.getTempFilename()
+
+        # Inject rules into temporary txt file
+        with open(tempRulesName, "w") as tempRules:
+            tempRules.write(txtRules.value)
+
+        # Use temporary file as rules file
+        alg.setParameterValue('rules', tempRulesName)
+        alg.parameters.remove(txtRules)
+
     alg.processCommand()
 
     # re-add the previous output
     alg.addOutput(output)
+    alg.addParameter(color)
+    alg.addParameter(txtRules)
 
 
 def processOutputs(alg):
@@ -91,7 +106,7 @@ def processOutputs(alg):
     rasters = [alg.exportedLayers[f] for f in alg.getParameterValue('map').split(',')]
     output_dir = alg.getOutputValue('output_dir')
     for raster in rasters:
-        command = u"r.out.gdal createopt=\"TFW=YES,COMPRESS=LZW\" input={} output=\"{}\" --overwrite".format(
+        command = u"r.out.gdal -t createopt=\"TFW=YES,COMPRESS=LZW\" input={} output=\"{}\" --overwrite".format(
             raster,
             os.path.join(output_dir, raster + '.tif')
         )