diff --git a/.ghci b/.ghci
--- a/.ghci
+++ b/.ghci
@@ -1,1 +1,1 @@
-:set -isrc-lib:src-exe:src-test:dist/build/autogen -optP-include -optPdist/build/autogen/cabal_macros.h
+:set -isrc-lib:src-exe:src-test:dist/build/autogen -optP-include -optPdist/build/autogen/cabal_macros.h -Wall -fno-warn-tabs
diff --git a/changelog.markdown b/changelog.markdown
--- a/changelog.markdown
+++ b/changelog.markdown
@@ -49,5 +49,9 @@
 * Added file **.ghci**.
 * Replaced use of module **ToolShed.Defaultable** with **Data.Default**.
 * Tested with **ghc-8.0.1**.
+
 ## 0.0.1.7
 * Removed dependency on **Distribution.Package.PackageName**
+
+## 0.0.1.8
+Replaced '+ negate' with 'subtract' in **FishFood.Test.QuickCheck.Profiler**.
diff --git a/debian/DEBIAN/control b/debian/DEBIAN/control
--- a/debian/DEBIAN/control
+++ b/debian/DEBIAN/control
@@ -1,5 +1,5 @@
 Package:	fishfood
-Version:	0.0.1.7-1
+Version:	0.0.1.8-1
 Section:	utils
 Priority:	optional
 Architecture:	amd64
diff --git a/fishfood.cabal b/fishfood.cabal
--- a/fishfood.cabal
+++ b/fishfood.cabal
@@ -14,7 +14,7 @@
 -- along with FishFood.  If not, see <http://www.gnu.org/licenses/>.
 
 Name:		fishfood
-Version:	0.0.1.7
+Version:	0.0.1.8
 Cabal-version:	>= 1.10
 Copyright:	(C) 2013-2015 Dr. Alistair Ward
 License:	GPL
@@ -25,7 +25,7 @@
 Build-type:	Simple
 Description:	Counts the number of files in a set of bins, each of which holds only those files which fall within a specific size-interval.
 Category:	Utils
-Tested-with:	GHC == 7.4, GHC == 7.6, GHC == 7.8, GHC == 7.10.1, GHC == 8.0.1
+Tested-with:	GHC == 7.4, GHC == 7.6, GHC == 7.8, GHC == 7.10, GHC == 8.0
 Homepage:	http://functionalley.eu
 Maintainer:	mailto:fishfood@functionalley.eu
 Bug-reports:	mailto:fishfood@functionalley.eu
@@ -45,7 +45,7 @@
     type:	git
     location:	https://github.com/functionalley/FishFood
 
--- Enable using: 'cabal configure -f llvm'.
+-- Enable using: 'runhaskell Setup configure -f llvm --verbose'.
 flag llvm
     Description:	Whether the 'llvm' compiler-backend has been installed and is required for code-generation.
     Manual:		True
@@ -72,17 +72,17 @@
         mtl,
         toolshed >= 0.17
 
-    if impl(ghc >= 7.4.1)
-        GHC-prof-options:	-fprof-auto -fprof-cafs
-    else
-        GHC-prof-options:	-auto-all -caf-all
-
     if impl(ghc >= 7.0)
         if flag(llvm)
             GHC-options:	-fllvm
 
-        if impl(ghc >= 8.0)
-            GHC-options:	-Wredundant-constraints
+        if impl(ghc >= 7.4.1)
+            GHC-prof-options:	-fprof-auto -fprof-cafs
+    
+            if impl(ghc >= 8.0)
+                GHC-options:	-j -Wredundant-constraints
+        else
+            GHC-prof-options:	-auto-all -caf-all
 
 Executable fishfood
     Default-language:	Haskell2010
@@ -98,19 +98,19 @@
         mtl,
         toolshed >= 0.17
 
-    if impl(ghc >= 7.4.1)
-        GHC-prof-options:	-fprof-auto -fprof-cafs
-    else
-        GHC-prof-options:	-auto-all -caf-all
-
     if impl(ghc >= 7.0)
         GHC-options:	-rtsopts
 
         if flag(llvm)
             GHC-options:	-fllvm
 
-        if impl(ghc >= 8.0)
-            GHC-options:	-Wredundant-constraints
+        if impl(ghc >= 7.4.1)
+            GHC-prof-options:	-fprof-auto -fprof-cafs
+    
+            if impl(ghc >= 8.0)
+                GHC-options:	-j -Wredundant-constraints
+        else
+            GHC-prof-options:	-auto-all -caf-all
 
 Test-Suite test
     Default-language:	Haskell2010
@@ -135,4 +135,4 @@
         toolshed >= 0.17
 
     if impl(ghc >= 8.0)
-        GHC-options:	-Wredundant-constraints
+        GHC-options:	-j -Wredundant-constraints
diff --git a/fishfood.spec b/fishfood.spec
--- a/fishfood.spec
+++ b/fishfood.spec
@@ -21,7 +21,7 @@
 
 Summary:	Calculates file-size frequency-distribution.
 Name:		fishfood
-Version:	0.0.1.7
+Version:	0.0.1.8
 Release:	1
 License:	GPLv3
 # From '/usr/share/doc/packages/rpm/GROUPS'.
diff --git a/src-test/FishFood/Test/QuickCheck/Profiler.hs b/src-test/FishFood/Test/QuickCheck/Profiler.hs
--- a/src-test/FishFood/Test/QuickCheck/Profiler.hs
+++ b/src-test/FishFood/Test/QuickCheck/Profiler.hs
@@ -40,7 +40,7 @@
 results :: IO [Test.QuickCheck.Result]
 results	= mapM Test.QuickCheck.quickCheckResult [prop_calculateProbabilityMassFunction, prop_calculateFileSizeFrequencyDistribution, prop_attendance]	where
 	prop_calculateProbabilityMassFunction, prop_calculateFileSizeFrequencyDistribution, prop_attendance :: Test.QuickCheck.Data.CommandOptions.CommandOptions -> [Data.File.FileSize] -> Test.QuickCheck.Property
-	prop_calculateProbabilityMassFunction commandOptions fileSizes	= not (null fileSizes) && ToolShed.SelfValidate.isValid commandOptions' ==> Test.QuickCheck.label "prop_calculateProbabilityMassFunction" . (<= recip 1000000) . (+ negate 1) . sum . Data.Either.rights {-probabilities-} . map Profiler.getValue . fst {-distribution-} . Control.Monad.Writer.runWriter . Profiler.calculateFileSizeDistribution commandOptions' $ map abs fileSizes	where
+	prop_calculateProbabilityMassFunction commandOptions fileSizes	= not (null fileSizes) && ToolShed.SelfValidate.isValid commandOptions' ==> Test.QuickCheck.label "prop_calculateProbabilityMassFunction" . (<= recip 1000000) . subtract 1 . sum . Data.Either.rights {-probabilities-} . map Profiler.getValue . fst {-distribution-} . Control.Monad.Writer.runWriter . Profiler.calculateFileSizeDistribution commandOptions' $ map abs fileSizes	where
 		commandOptions'	= commandOptions { Data.CommandOptions.getDeriveProbabilityMassFunction	= True }
 
 	prop_calculateFileSizeFrequencyDistribution commandOptions fileSizes	= not (null fileSizes) && ToolShed.SelfValidate.isValid commandOptions' ==> Test.QuickCheck.label "prop_calculateFileSizeFrequencyDistribution" . (== length fileSizes) . sum . Data.Either.lefts {-frequency-} . map Profiler.getValue . fst {-distribution-} . Control.Monad.Writer.runWriter . Profiler.calculateFileSizeDistribution commandOptions' $ map abs fileSizes	where
