diff --git a/cmd/ca/ca.go b/cmd/ca/ca.go
index e9f725c..b623751 100644
--- a/cmd/ca/ca.go
+++ b/cmd/ca/ca.go
@@ -96,7 +96,7 @@ func signingDates(defaultDuration time.Duration) (from, until time.Time) {
 	} else {
 		from, err = time.Parse(time.RFC3339, validFrom)
 		if err != nil {
-			fmt.Fprintln(os.Stderr, "--valid-from %s: not a valid RFC3339-format timestamp\n")
+			fmt.Fprintf(os.Stderr, "--valid-from %q: not a valid RFC3339-format timestamp\n", validFrom)
 			os.Exit(1)
 		}
 	}
@@ -105,7 +105,7 @@ func signingDates(defaultDuration time.Duration) (from, until time.Time) {
 	} else {
 		until, err = time.Parse(time.RFC3339, validUntil)
 		if err != nil {
-			fmt.Fprintln(os.Stderr, "--valid-until %s: not a valid RFC3339-format timestamp\n")
+			fmt.Fprintf(os.Stderr, "--valid-until %q: not a valid RFC3339-format timestamp\n", validUntil)
 			os.Exit(1)
 		}
 	}
diff --git a/cmd/inspect/display_structured.go b/cmd/inspect/display_structured.go
index d1891a0..0b48210 100644
--- a/cmd/inspect/display_structured.go
+++ b/cmd/inspect/display_structured.go
@@ -28,7 +28,7 @@ func displayStructuredJSON() {
 	enc := json.NewEncoder(os.Stdout)
 	enc.SetIndent("", "  ")
 	if err := enc.Encode(displayStructures); err != nil {
-		fmt.Fprintln(os.Stderr, "failed to encode as JSON: %v\n", aura.Red(err))
+		fmt.Fprintf(os.Stderr, "failed to encode as JSON: %v\n", aura.Red(err))
 		os.Exit(1)
 	}
 }
@@ -37,7 +37,7 @@ func displayStructuredYAML() {
 	enc := yaml.NewEncoder(os.Stdout)
 	enc.SetIndent(2)
 	if err := enc.Encode(displayStructures); err != nil {
-		fmt.Fprintln(os.Stderr, "failed to encode as YAML: %v\n", aura.Red(err))
+		fmt.Fprintf(os.Stderr, "failed to encode as YAML: %v\n", aura.Red(err))
 		os.Exit(2)
 	}
 }