diff --git a/cmd/entries/edit.go b/cmd/entries/edit.go
index b314ff8..9d79c9d 100644
--- a/cmd/entries/edit.go
+++ b/cmd/entries/edit.go
@@ -243,7 +243,7 @@ func EditCmd() *cobra.Command {
 				os.Exit(1)
 			}
 
-			descriptionInput = strings.TrimSpace(descriptionInput)
+			descriptionInput = ui.SanitizeSingleLine(descriptionInput)
 			if descriptionInput == "" {
 				descriptionInput = currentDescription
 			}
diff --git a/cmd/entries/manual.go b/cmd/entries/manual.go
index babdb45..a24f86d 100644
--- a/cmd/entries/manual.go
+++ b/cmd/entries/manual.go
@@ -102,7 +102,7 @@ func ManualCmd() *cobra.Command {
 					os.Exit(1)
 				}
 
-				projectInput = strings.TrimSpace(projectInput)
+				projectInput = ui.SanitizeSingleLine(projectInput)
 				if projectInput == "" {
 					projectName = projectHint
 				} else {
@@ -249,7 +249,7 @@ func ManualCmd() *cobra.Command {
 					os.Exit(1)
 				}
 
-				descVal = strings.TrimSpace(descVal)
+				descVal = ui.SanitizeSingleLine(descVal)
 				if descVal != "" {
 					description = descVal
 				}
diff --git a/cmd/milestones/start.go b/cmd/milestones/start.go
index 92fea4a..3bad29d 100644
--- a/cmd/milestones/start.go
+++ b/cmd/milestones/start.go
@@ -36,7 +36,7 @@ func StartCmd() *cobra.Command {
 				os.Exit(1)
 			}
 
-			milestoneName := args[0]
+			milestoneName := ui.SanitizeSingleLine(args[0])
 
 			// Check if there's already an active milestone
 			activeMilestone, err := db.GetActiveMilestoneForProject(projectName)
diff --git a/cmd/tracking/start.go b/cmd/tracking/start.go
index 34fbb3d..23eb7f8 100644
--- a/cmd/tracking/start.go
+++ b/cmd/tracking/start.go
@@ -52,7 +52,7 @@ func StartCmd() *cobra.Command {
 
 			description := ""
 			if len(args) > 0 {
-				description = args[0]
+				description = ui.SanitizeSingleLine(args[0])
 			}
 
 			var hourlyRate *float64
diff --git a/internal/ui/ui.go b/internal/ui/ui.go
index a55791e..7cb467c 100644
--- a/internal/ui/ui.go
+++ b/internal/ui/ui.go
@@ -3,6 +3,7 @@ package ui
 import (
 	"fmt"
 	"os"
+	"strings"
 	"time"
 
 	"github.com/DylanDevelops/tmpo/internal/shell"
@@ -159,6 +160,13 @@ func FormatFileSize(bytes int64) string {
 	return fmt.Sprintf("%.1f MB", float64(bytes)/(1024*1024))
 }
 
+func SanitizeSingleLine(s string) string {
+	s = strings.ReplaceAll(s, "\r\n", " ")
+	s = strings.ReplaceAll(s, "\r", " ")
+	s = strings.ReplaceAll(s, "\n", " ")
+	return strings.TrimSpace(s)
+}
+
 func FormatDuration(d time.Duration) string {
 	totalSeconds := int(d.Seconds())
 	days := totalSeconds / 86400
diff --git a/internal/ui/ui_test.go b/internal/ui/ui_test.go
index 87be392..0fb1620 100644
--- a/internal/ui/ui_test.go
+++ b/internal/ui/ui_test.go
@@ -164,6 +164,77 @@ func TestFormatFileSize(t *testing.T) {
 	}
 }
 
+func TestSanitizeSingleLine(t *testing.T) {
+	tests := []struct {
+		name     string
+		input    string
+		expected string
+	}{
+		{
+			name:     "plain string unchanged",
+			input:    "hello world",
+			expected: "hello world",
+		},
+		{
+			name:     "trims leading and trailing whitespace",
+			input:    "  hello world  ",
+			expected: "hello world",
+		},
+		{
+			name:     "replaces newline with space",
+			input:    "hello\nworld",
+			expected: "hello world",
+		},
+		{
+			name:     "replaces carriage return with space",
+			input:    "hello\rworld",
+			expected: "hello world",
+		},
+		{
+			name:     "replaces CRLF with space",
+			input:    "hello\r\nworld",
+			expected: "hello world",
+		},
+		{
+			name:     "replaces multiple newlines",
+			input:    "hello\n\nworld",
+			expected: "hello  world",
+		},
+		{
+			name:     "trims trailing newline",
+			input:    "hello\n",
+			expected: "hello",
+		},
+		{
+			name:     "trims leading newline",
+			input:    "\nhello",
+			expected: "hello",
+		},
+		{
+			name:     "empty string stays empty",
+			input:    "",
+			expected: "",
+		},
+		{
+			name:     "only whitespace becomes empty",
+			input:    "   \n\t  ",
+			expected: "",
+		},
+		{
+			name:     "mixed newlines and spaces",
+			input:    "  something blah blah blah \n  ",
+			expected: "something blah blah blah",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := SanitizeSingleLine(tt.input)
+			assert.Equal(t, tt.expected, result)
+		})
+	}
+}
+
 func TestFormatDuration(t *testing.T) {
 	tests := []struct {
 		name     string