diff --git a/cmd/restic/cmd_forget.go b/cmd/restic/cmd_forget.go
index fbe4c1c8a..caa205a45 100644
--- a/cmd/restic/cmd_forget.go
+++ b/cmd/restic/cmd_forget.go
@@ -99,8 +99,40 @@ func init() {
 	addPruneOptions(cmdForget)
 }
 
+func verifyForgetOptions(opts *ForgetOptions) error {
+	var negValFound = false
+
+	if opts.Last < -1 || opts.Hourly < -1 || opts.Daily < -1 || opts.Weekly < -1 ||
+		opts.Monthly < -1 || opts.Yearly < -1 {
+		negValFound = true
+	}
+
+	if !negValFound {
+		// durations := [6]restic.Duration{opts.Within, opts.WithinHourly, opts.WithinDaily,
+		// 	opts.WithinMonthly, opts.WithinWeekly, opts.WithinYearly}
+		for _, d := range [6]restic.Duration{opts.Within, opts.WithinHourly, opts.WithinDaily,
+			opts.WithinMonthly, opts.WithinWeekly, opts.WithinYearly} {
+			if d.Hours < -1 || d.Days < -1 || d.Months < -1 || d.Years < -1 {
+				negValFound = true
+				break
+			}
+		}
+	}
+
+	if negValFound {
+		return errors.Fatal("negative values other than -1 are not allowed for --keep-* options")
+	}
+
+	return nil
+}
+
 func runForget(ctx context.Context, opts ForgetOptions, gopts GlobalOptions, args []string) error {
-	err := verifyPruneOptions(&pruneOptions)
+	err := verifyForgetOptions(&opts)
+	if err != nil {
+		return err
+	}
+
+	err = verifyPruneOptions(&pruneOptions)
 	if err != nil {
 		return err
 	}
diff --git a/cmd/restic/cmd_forget_test.go b/cmd/restic/cmd_forget_test.go
new file mode 100644
index 000000000..778df4549
--- /dev/null
+++ b/cmd/restic/cmd_forget_test.go
@@ -0,0 +1,50 @@
+package main
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/restic/restic/internal/restic"
+	rtest "github.com/restic/restic/internal/test"
+)
+
+func TestPreventNegativeForgetOptionValues(t *testing.T) {
+	invalidForgetOpts := []ForgetOptions{
+		{Last: -2},
+		{Hourly: -2},
+		{Daily: -2},
+		{Weekly: -2},
+		{Monthly: -2},
+		{Yearly: -2},
+		{Within: restic.Duration{Hours: -2}},
+		{Within: restic.Duration{Days: -2}},
+		{Within: restic.Duration{Months: -2}},
+		{Within: restic.Duration{Years: -2}},
+		{WithinHourly: restic.Duration{Hours: -2}},
+		{WithinHourly: restic.Duration{Days: -2}},
+		{WithinHourly: restic.Duration{Months: -2}},
+		{WithinHourly: restic.Duration{Years: -2}},
+		{WithinDaily: restic.Duration{Hours: -2}},
+		{WithinDaily: restic.Duration{Days: -2}},
+		{WithinDaily: restic.Duration{Months: -2}},
+		{WithinDaily: restic.Duration{Years: -2}},
+		{WithinWeekly: restic.Duration{Hours: -2}},
+		{WithinWeekly: restic.Duration{Days: -2}},
+		{WithinWeekly: restic.Duration{Months: -2}},
+		{WithinWeekly: restic.Duration{Years: -2}},
+		{WithinMonthly: restic.Duration{Hours: -2}},
+		{WithinMonthly: restic.Duration{Days: -2}},
+		{WithinMonthly: restic.Duration{Months: -2}},
+		{WithinMonthly: restic.Duration{Years: -2}},
+		{WithinYearly: restic.Duration{Hours: -2}},
+		{WithinYearly: restic.Duration{Days: -2}},
+		{WithinYearly: restic.Duration{Months: -2}},
+		{WithinYearly: restic.Duration{Years: -2}},
+	}
+
+	for _, opts := range invalidForgetOpts {
+		err := verifyForgetOptions(&opts)
+		rtest.Assert(t, err != nil, fmt.Sprintf("should have returned error for %+v", opts))
+		rtest.Equals(t, "Fatal: negative values other than -1 are not allowed for --keep-* options", err.Error())
+	}
+}