diff --git a/gui/src/client/api.ts b/gui/src/client/api.ts
index 1271caab..cffdc183 100644
--- a/gui/src/client/api.ts
+++ b/gui/src/client/api.ts
@@ -438,6 +438,9 @@ export function makeClient(root: string, token: Maybe<string> = undefined, f = f
       // eslint-disable-next-line no-return-await
       return await parseRequest(url, {
         body,
+        headers: {
+          'Content-Type': 'application/json',
+        },
         method: 'POST',
       });
     },
diff --git a/gui/src/client/utils.ts b/gui/src/client/utils.ts
index d1d69141..20742556 100644
--- a/gui/src/client/utils.ts
+++ b/gui/src/client/utils.ts
@@ -3,7 +3,7 @@ import { ChainPipeline, HighresParams, ModelParams, Txt2ImgParams, UpscaleParams
 export interface PipelineVariable {
   parameter: 'prompt' | 'cfg' | 'seed' | 'steps';
   input: string;
-  values: Array<string>;
+  values: Array<number | string>;
 }
 
 export interface PipelineGrid {
diff --git a/gui/src/components/control/VariableControl.tsx b/gui/src/components/control/VariableControl.tsx
index cd159954..abdbce13 100644
--- a/gui/src/components/control/VariableControl.tsx
+++ b/gui/src/components/control/VariableControl.tsx
@@ -74,7 +74,7 @@ export function VariableControl(props: VariableControlProps) {
   </Stack>;
 }
 
-export function rangeSplit(parameter: string, value: string): Array<string> {
+export function rangeSplit(parameter: string, value: string): Array<number | string> {
   // string values
   if (parameter === 'prompt') {
     return value.split('\n');
@@ -86,7 +86,7 @@ export function rangeSplit(parameter: string, value: string): Array<string> {
 export const EXPR_STRICT_NUMBER = /^[0-9]+$/;
 export const EXPR_NUMBER_RANGE = /^([0-9]+)-([0-9]+)$/;
 
-export function expandRanges(range: string): Array<string> {
+export function expandRanges(range: string): Array<string | number> {
   if (EXPR_STRICT_NUMBER.test(range)) {
     // entirely numeric, return without parsing
     return [range];
@@ -99,7 +99,7 @@ export function expandRanges(range: string): Array<string> {
       const start = parseInt(startStr, 10);
       const end = parseInt(endStr, 10);
 
-      return new Array(end - start).fill(0).map((_value, idx) => (idx + start).toFixed(0));
+      return new Array(end - start).fill(0).map((_value, idx) => idx + start);
     }
   }