diff --git a/api/iteration.go b/api/iteration.go
index 8fd3fa53e..f0632c125 100644
--- a/api/iteration.go
+++ b/api/iteration.go
@@ -102,8 +102,8 @@ func NewIteration(dir string, filenames []string) (*Iteration, error) {
 		// is still bad. Has the user modified their path in some way?
 		return nil, newIterationError(msgGenericPathError, iter.Dir)
 	}
-	iter.TrackID = segments[1]
-	iter.Problem = segments[2]
+	iter.TrackID = strings.ToLower(segments[1])
+	iter.Problem = strings.ToLower(segments[2])
 
 	for _, filename := range filenames {
 		fileContents, err := readFileAsUTF8String(filename)
diff --git a/api/iteration_darwin_test.go b/api/iteration_darwin_test.go
new file mode 100644
index 000000000..d910d354f
--- /dev/null
+++ b/api/iteration_darwin_test.go
@@ -0,0 +1,38 @@
+package api
+
+import (
+	"path/filepath"
+	"runtime"
+	"testing"
+)
+
+func TestNewIteration_CaseSensitive(t *testing.T) {
+	_, path, _, _ := runtime.Caller(0)
+	dir := filepath.Join(path, "..", "..", "fixtures", "iteration")
+
+	testCases := []map[string][]string{
+		{
+			"file": []string{filepath.Join(dir, "python", "leap", "one.py")},
+		},
+		{
+			"file": []string{filepath.Join(dir, "Python", "leap", "one.py")},
+		},
+		{
+			"file": []string{filepath.Join(dir, "Python", "Leap", "one.py")},
+		},
+	}
+
+	for _, testCase := range testCases {
+		iter, err := NewIteration(dir, testCase["file"])
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if iter.TrackID != "python" {
+			t.Errorf("Expected language to be python, was %s", iter.TrackID)
+		}
+		if iter.Problem != "leap" {
+			t.Errorf("Expected problem to be leap, was %s", iter.Problem)
+		}
+	}
+}
diff --git a/cmd/submit.go b/cmd/submit.go
index 146101382..5ba006295 100644
--- a/cmd/submit.go
+++ b/cmd/submit.go
@@ -7,10 +7,10 @@ import (
 	"os"
 	"path/filepath"
 
-	"github.com/urfave/cli"
 	"github.com/exercism/cli/api"
 	"github.com/exercism/cli/config"
 	"github.com/exercism/cli/paths"
+	"github.com/urfave/cli"
 )
 
 // Submit posts an iteration to the API.
@@ -89,7 +89,7 @@ func Submit(ctx *cli.Context) error {
 
 	iteration, err := api.NewIteration(dir, files)
 	if err != nil {
-		log.Fatalf("Unable to submit - %s", err)
+		log.Fatalf("unable to submit - %s", err)
 	}
 	iteration.Key = c.APIKey
 	iteration.Comment = ctx.String("comment")