diff --git a/generator_test.go b/generator_test.go
index 95c47db..103c2b2 100644
--- a/generator_test.go
+++ b/generator_test.go
@@ -10,8 +10,19 @@ import (
 	"testing"
 )
 
+func opensslOutput(r GeneratorResult) {
+	switch r {
+	case GeneratorFoundPossiblePrime:
+		os.Stderr.WriteString(".")
+	case GeneratorFirstConfirmation:
+		os.Stderr.WriteString("+")
+	case GeneratorSafePrimeFound:
+		os.Stderr.WriteString("*\n")
+	}
+}
+
 func execGeneratorIntegration(t *testing.T, bitsize int, generator Generator) {
-	dh, err := Generate(bitsize, generator, nil)
+	dh, err := Generate(bitsize, generator, opensslOutput)
 	if err != nil {
 		t.Fatalf("Unable to generate DH params: %s", err)
 	}
diff --git a/validate_test.go b/validate_test.go
index d1ba88d..094b957 100644
--- a/validate_test.go
+++ b/validate_test.go
@@ -3,7 +3,7 @@ package dhparam
 import "testing"
 
 func TestCheckOwn(t *testing.T) {
-	dh, err := Generate(512, 2, nil)
+	dh, err := Generate(512, 2, opensslOutput)
 	if err != nil {
 		t.Fatalf("Could not generate DH parameters: %s", err)
 	}