diff --git a/compact.go b/compact.go
index 280cbd4..b1c0cba 100644
--- a/compact.go
+++ b/compact.go
@@ -32,10 +32,10 @@ func (compactOptions CompactOptions) Normalised() CompactOptions {
 	if compactOptions.Output == "" {
 		compactOptions.Output = defaultArchiveOutputDirectory
 	}
+	compactOptions.Format = lowerText(core.Trim(compactOptions.Format))
 	if compactOptions.Format == "" {
 		compactOptions.Format = "gzip"
 	}
-	compactOptions.Format = lowerText(core.Trim(compactOptions.Format))
 	return compactOptions
 }
 
diff --git a/compact_test.go b/compact_test.go
index 350449a..fd7cfce 100644
--- a/compact_test.go
+++ b/compact_test.go
@@ -223,6 +223,16 @@ func TestCompact_CompactOptions_Good_ValidateNormalisesFormatCase(t *testing.T)
 	assert.Equal(t, "zstd", options.Format)
 }
 
+func TestCompact_CompactOptions_Good_ValidateWhitespaceFormatDefaultsToGzip(t *testing.T) {
+	options := (CompactOptions{
+		Before: time.Now().Add(-24 * time.Hour),
+		Format: "   ",
+	}).Normalised()
+
+	assert.Equal(t, "gzip", options.Format)
+	require.NoError(t, options.Validate())
+}
+
 func TestCompact_CompactOptions_Bad_ValidateUnsupportedFormat(t *testing.T) {
 	err := (CompactOptions{
 		Before: time.Now().Add(-24 * time.Hour),