diff --git a/pkg/bar_chart_handler_test.go b/pkg/bar_chart_handler_test.go
index cd44716..463a8c1 100644
--- a/pkg/bar_chart_handler_test.go
+++ b/pkg/bar_chart_handler_test.go
@@ -56,7 +56,7 @@ func TestGetBarChart(t *testing.T) {
 		if resp.StatusCode == http.StatusOK {
 			assert.Equal(t, "image/png", resp.Header.Get("Content-Type"))
 		} else {
-			assert.Equal(t, "application/json; charset=UTF-8", resp.Header.Get("Content-Type"))
+			assert.Equal(t, "application/json", resp.Header.Get("Content-Type"))
 		}
 	}
 }
diff --git a/pkg/donut_chart_handler_test.go b/pkg/donut_chart_handler_test.go
index 8369cb9..2f06206 100644
--- a/pkg/donut_chart_handler_test.go
+++ b/pkg/donut_chart_handler_test.go
@@ -52,7 +52,7 @@ func TestGetDonutChart(t *testing.T) {
 		if resp.StatusCode == http.StatusOK {
 			assert.Equal(t, "image/png", resp.Header.Get("Content-Type"))
 		} else {
-			assert.Equal(t, "application/json; charset=UTF-8", resp.Header.Get("Content-Type"))
+			assert.Equal(t, "application/json", resp.Header.Get("Content-Type"))
 		}
 	}
 }
diff --git a/pkg/funnel_chart_handler_test.go b/pkg/funnel_chart_handler_test.go
index 3010fd3..5c0508e 100644
--- a/pkg/funnel_chart_handler_test.go
+++ b/pkg/funnel_chart_handler_test.go
@@ -59,7 +59,7 @@ func TestGetFunnelChart(t *testing.T) {
 		if resp.StatusCode == http.StatusOK {
 			assert.Equal(t, "image/png", resp.Header.Get("Content-Type"))
 		} else {
-			assert.Equal(t, "application/json; charset=UTF-8", resp.Header.Get("Content-Type"))
+			assert.Equal(t, "application/json", resp.Header.Get("Content-Type"))
 		}
 	}
 }
diff --git a/pkg/line_chart_handler_test.go b/pkg/line_chart_handler_test.go
index 64f9158..ee31f09 100644
--- a/pkg/line_chart_handler_test.go
+++ b/pkg/line_chart_handler_test.go
@@ -57,7 +57,7 @@ func TestGetLineChart(t *testing.T) {
 		if resp.StatusCode == http.StatusOK {
 			assert.Equal(t, "image/png", resp.Header.Get("Content-Type"))
 		} else {
-			assert.Equal(t, "application/json; charset=UTF-8", resp.Header.Get("Content-Type"))
+			assert.Equal(t, "application/json", resp.Header.Get("Content-Type"))
 		}
 	}
 }
diff --git a/pkg/pie_chart_handler_test.go b/pkg/pie_chart_handler_test.go
index 02e4818..988ee3e 100644
--- a/pkg/pie_chart_handler_test.go
+++ b/pkg/pie_chart_handler_test.go
@@ -52,7 +52,7 @@ func TestGetPieChart(t *testing.T) {
 		if resp.StatusCode == http.StatusOK {
 			assert.Equal(t, "image/png", resp.Header.Get("Content-Type"))
 		} else {
-			assert.Equal(t, "application/json; charset=UTF-8", resp.Header.Get("Content-Type"))
+			assert.Equal(t, "application/json", resp.Header.Get("Content-Type"))
 		}
 	}
 }
diff --git a/pkg/radar_chart_handler_test.go b/pkg/radar_chart_handler_test.go
index 083c973..f5a9c45 100644
--- a/pkg/radar_chart_handler_test.go
+++ b/pkg/radar_chart_handler_test.go
@@ -59,7 +59,7 @@ func TestGetRadarChart(t *testing.T) {
 		if resp.StatusCode == http.StatusOK {
 			assert.Equal(t, "image/png", resp.Header.Get("Content-Type"))
 		} else {
-			assert.Equal(t, "application/json; charset=UTF-8", resp.Header.Get("Content-Type"))
+			assert.Equal(t, "application/json", resp.Header.Get("Content-Type"))
 		}
 	}
 }
diff --git a/pkg/table_chart_handler_test.go b/pkg/table_chart_handler_test.go
index bb09369..f7a9cbe 100644
--- a/pkg/table_chart_handler_test.go
+++ b/pkg/table_chart_handler_test.go
@@ -64,7 +64,7 @@ func TestGetTableChart(t *testing.T) {
 		if resp.StatusCode == http.StatusOK {
 			assert.Equal(t, "image/png", resp.Header.Get("Content-Type"))
 		} else {
-			assert.Equal(t, "application/json; charset=UTF-8", resp.Header.Get("Content-Type"))
+			assert.Equal(t, "application/json", resp.Header.Get("Content-Type"))
 		}
 	}
 }