diff --git a/internal/hclogutils/args_test.go b/internal/hclogutils/args_test.go
index 6323590..22dd976 100644
--- a/internal/hclogutils/args_test.go
+++ b/internal/hclogutils/args_test.go
@@ -195,6 +195,18 @@ func TestArgsToKeys(t *testing.T) {
 				"map1-key3",
 			},
 		},
+		"non-even-number-of-args": {
+			args: []interface{}{
+				"map1-key1", "map1-value1",
+				"map1-key2", "map1-value2",
+				"map1-key3",
+			},
+			expectedKeys: []string{
+				"map1-key1",
+				"map1-key2",
+				"map1-key3",
+			},
+		},
 		"multiple-different-keys": {
 			args: []interface{}{
 				"map1-key1", "map1-value1",
diff --git a/internal/logging/filtering_test.go b/internal/logging/filtering_test.go
index 19515f0..c70d297 100644
--- a/internal/logging/filtering_test.go
+++ b/internal/logging/filtering_test.go
@@ -98,7 +98,7 @@ func TestShouldOmit(t *testing.T) {
 	}
 }
 
-func TestShouldMask(t *testing.T) {
+func TestApplyMask(t *testing.T) {
 	t.Parallel()
 
 	testCases := map[string]struct {
@@ -144,6 +144,56 @@ func TestShouldMask(t *testing.T) {
 				},
 			},
 		},
+		"mask-log-by-non-even-args-cannot-mask-missing-value": {
+			lOpts: LoggerOpts{
+				MaskLogValueByKeys: []string{"K2", "k4"},
+			},
+			msg: testLogMsg,
+			argSlices: [][]interface{}{
+				{
+					"k1", "v1",
+					"k2", "v2",
+				},
+				{
+					"k3", "v3",
+					"k4",
+				},
+			},
+			expectedMsg: "System FOO has caused error BAR because of incorrectly configured BAZ",
+			expectedArgSlices: [][]interface{}{
+				{
+					"k1", "v1",
+					"k2", "***",
+				},
+				{
+					"k3", "v3",
+					"k4",
+				},
+			},
+		},
+		"mask-log-by-non-even-args": {
+			lOpts: LoggerOpts{
+				MaskLogValueByKeys: []string{"K2"},
+			},
+			msg: testLogMsg,
+			argSlices: [][]interface{}{
+				{
+					"k1", "v1",
+					"k2", "v2",
+					"k3", "v3",
+					"k4",
+				},
+			},
+			expectedMsg: "System FOO has caused error BAR because of incorrectly configured BAZ",
+			expectedArgSlices: [][]interface{}{
+				{
+					"k1", "v1",
+					"k2", "***",
+					"k3", "v3",
+					"k4",
+				},
+			},
+		},
 		"mask-log-matching-regexp-case-insensitive": {
 			lOpts: LoggerOpts{
 				MaskLogMatchingRegexp: []*regexp.Regexp{regexp.MustCompile("(?i)(foo|bar)")},