diff --git a/src/GitVersionCore/BranchConfigurationCalculator.cs b/src/GitVersionCore/BranchConfigurationCalculator.cs
index d63f83cf85..10a98ee588 100644
--- a/src/GitVersionCore/BranchConfigurationCalculator.cs
+++ b/src/GitVersionCore/BranchConfigurationCalculator.cs
@@ -4,6 +4,9 @@ namespace GitVersion
     using System.Collections.Generic;
     using System.Linq;
     using System.Text.RegularExpressions;
+
+    using JetBrains.Annotations;
+
     using LibGit2Sharp;
 
     public class BranchConfigurationCalculator
@@ -35,11 +38,22 @@ public static KeyValuePair<string, BranchConfig> GetBranchConfiguration(Commit c
             throw new Exception(string.Format(format, currentBranch.Name, string.Join(", ", matchingBranches.Select(b => b.Key))));
         }
 
-        static KeyValuePair<string, BranchConfig>[] LookupBranchConfiguration(Config config, Branch currentBranch)
+        static KeyValuePair<string, BranchConfig>[] LookupBranchConfiguration([NotNull] Config config, [NotNull] Branch currentBranch)
         {
+            if (config == null)
+            {
+                throw new ArgumentNullException("config");
+            }
+            
+            if (currentBranch == null)
+            {
+                throw new ArgumentNullException("currentBranch");
+            }
+            
             return config.Branches.Where(b => Regex.IsMatch(currentBranch.Name, "^" + b.Key, RegexOptions.IgnoreCase)).ToArray();
         }
 
+
         static KeyValuePair<string, BranchConfig> InheritBranchConfiguration(bool onlyEvaluateTrackedBranches, IRepository repository, Commit currentCommit, Branch currentBranch, KeyValuePair<string, BranchConfig> keyValuePair, BranchConfig branchConfiguration, Config config, IList<Branch> excludedInheritBranches)
         {
             using (Logger.IndentLog("Attempting to inherit branch configuration from parent branch"))
@@ -104,11 +118,15 @@ static KeyValuePair<string, BranchConfig> InheritBranchConfiguration(bool onlyEv
                 else
                     errorMessage = "Failed to inherit Increment branch configuration, ended up with: " + string.Join(", ", possibleParents.Select(p => p.Name));
 
-                var developBranch = repository.Branches.FirstOrDefault(b => Regex.IsMatch(b.Name, "^develop", RegexOptions.IgnoreCase));
-                var branchName = developBranch != null ? developBranch.Name : "master";
+                var chosenBranch = repository.Branches.FirstOrDefault(b => Regex.IsMatch(b.Name, "^develop", RegexOptions.IgnoreCase)
+                                                                           || Regex.IsMatch(b.Name, "master$", RegexOptions.IgnoreCase));
+                if (chosenBranch == null)
+                    throw new InvalidOperationException("Could not find a 'develop' or 'master' branch, neither locally nor remotely.");
 
+                var branchName = chosenBranch.Name;
                 Logger.WriteWarning(errorMessage + Environment.NewLine + Environment.NewLine + "Falling back to " + branchName + " branch config");
-                var value = GetBranchConfiguration(currentCommit, repository, onlyEvaluateTrackedBranches, config, repository.Branches[branchName]).Value;
+
+                var value = GetBranchConfiguration(currentCommit, repository, onlyEvaluateTrackedBranches, config, chosenBranch).Value;
                 return new KeyValuePair<string, BranchConfig>(
                     keyValuePair.Key,
                     new BranchConfig(branchConfiguration)
diff --git a/src/GitVersionCore/LibGitExtensions.cs b/src/GitVersionCore/LibGitExtensions.cs
index c50f1744ed..2bc9f6a4f6 100644
--- a/src/GitVersionCore/LibGitExtensions.cs
+++ b/src/GitVersionCore/LibGitExtensions.cs
@@ -6,6 +6,9 @@ namespace GitVersion
     using System.Linq;
     using System.Text;
     using GitVersion.Helpers;
+
+    using JetBrains.Annotations;
+
     using LibGit2Sharp;
 
     static class LibGitExtensions
@@ -44,13 +47,33 @@ public static SemanticVersion LastVersionTagOnBranch(this Branch branch, IReposi
             .FirstOrDefault();
         }
 
-        public static Commit FindCommitBranchWasBranchedFrom(this Branch branch, IRepository repository, params Branch[] excludedBranches)
+
+        public static Commit FindCommitBranchWasBranchedFrom([NotNull] this Branch branch, IRepository repository, params Branch[] excludedBranches)
         {
+            const string missingTipFormat = "{0} has no tip. Please see http://example.com/docs for information on how to fix this.";
+
+            if (branch == null)
+            {
+                throw new ArgumentNullException("branch");
+            }
+
             using (Logger.IndentLog("Finding branch source"))
             {
+                if (branch.Tip == null)
+                {
+                    Logger.WriteWarning(String.Format(missingTipFormat, branch.Name));
+                    return null;
+                }
+
                 var otherBranches = repository.Branches.Except(excludedBranches).Where(b => IsSameBranch(branch, b)).ToList();
                 var mergeBases = otherBranches.Select(b =>
                 {
+                    if (b.Tip == null)
+                    {
+                        Logger.WriteWarning(String.Format(missingTipFormat, b.Name));
+                        return null;
+                    }
+
                     var otherCommit = b.Tip;
                     if (b.Tip.Parents.Contains(branch.Tip))
                     {
@@ -63,17 +86,23 @@ public static Commit FindCommitBranchWasBranchedFrom(this Branch branch, IReposi
             }
         }
 
+
         static bool IsSameBranch(Branch branch, Branch b)
         {
             return (b.IsRemote ? b.Name.Replace(b.Remote.Name + "/", string.Empty) : b.Name) != branch.Name;
         }
 
-        public static IEnumerable<Branch> GetBranchesContainingCommit(this Commit commit, IRepository repository, bool onlyTrackedBranches)
+        public static IEnumerable<Branch> GetBranchesContainingCommit([NotNull] this Commit commit, IRepository repository, bool onlyTrackedBranches)
         {
+            if (commit == null)
+            {
+                throw new ArgumentNullException("commit");
+            }
+
             var directBranchHasBeenFound = false;
             foreach (var branch in repository.Branches)
             {
-                if (branch.Tip.Sha != commit.Sha || (onlyTrackedBranches && !branch.IsTracking))
+                if (branch.Tip != null && branch.Tip.Sha != commit.Sha || (onlyTrackedBranches && !branch.IsTracking))
                 {
                     continue;
                 }
diff --git a/src/GitVersionCore/Logger.cs b/src/GitVersionCore/Logger.cs
index 6acffd0c10..d880b0f9cc 100644
--- a/src/GitVersionCore/Logger.cs
+++ b/src/GitVersionCore/Logger.cs
@@ -6,12 +6,14 @@ namespace GitVersion
 
     public static class Logger
     {
+        static readonly Regex ObscurePasswordRegex = new Regex("(https?://)(.+)(:.+@)", RegexOptions.Compiled);
         static string indent = string.Empty;
 
         public static Action<string> WriteInfo { get; private set; }
         public static Action<string> WriteWarning { get; private set; }
         public static Action<string> WriteError { get; private set; }
 
+
         static Logger()
         {
             Reset();
@@ -33,8 +35,7 @@ static Action<string> ObscurePassword(Action<string> info)
         {
             Action<string> logAction = s =>
             {
-                var rgx = new Regex("(https?://)(.+)(:.+@)");
-                s = rgx.Replace(s, "$1$2:*******@");
+                s = ObscurePasswordRegex.Replace(s, "$1$2:*******@");
                 info(s);
             };
             return logAction;