diff --git a/src/InputHandler.test.ts b/src/InputHandler.test.ts
index f2e8d93e92..b9a494f9ee 100644
--- a/src/InputHandler.test.ts
+++ b/src/InputHandler.test.ts
@@ -495,6 +495,46 @@ describe('InputHandler', () => {
       assert.equal(term.curAttrData.getBgColorMode(), 0);
       assert.equal(term.curAttrData.getBgColor(), -1);
     });
+    it('colormode transition RGB to 256', () => {
+      // enter RGB for FG and BG
+      term.writeSync(`\x1b[38;2;1;2;3;48;2;4;5;6m`);
+      // enter 256 for FG and BG
+      term.writeSync(`\x1b[38;5;255;48;5;255m`);
+      assert.equal(term.curAttrData.getFgColorMode(), Attributes.CM_P256);
+      assert.equal(term.curAttrData.getFgColor(), 255);
+      assert.equal(term.curAttrData.getBgColorMode(), Attributes.CM_P256);
+      assert.equal(term.curAttrData.getBgColor(), 255);
+    });
+    it('colormode transition RGB to 16', () => {
+      // enter RGB for FG and BG
+      term.writeSync(`\x1b[38;2;1;2;3;48;2;4;5;6m`);
+      // enter 16 for FG and BG
+      term.writeSync(`\x1b[37;47m`);
+      assert.equal(term.curAttrData.getFgColorMode(), Attributes.CM_P16);
+      assert.equal(term.curAttrData.getFgColor(), 7);
+      assert.equal(term.curAttrData.getBgColorMode(), Attributes.CM_P16);
+      assert.equal(term.curAttrData.getBgColor(), 7);
+    });
+    it('colormode transition 16 to 256', () => {
+      // enter 16 for FG and BG
+      term.writeSync(`\x1b[37;47m`);
+      // enter 256 for FG and BG
+      term.writeSync(`\x1b[38;5;255;48;5;255m`);
+      assert.equal(term.curAttrData.getFgColorMode(), Attributes.CM_P256);
+      assert.equal(term.curAttrData.getFgColor(), 255);
+      assert.equal(term.curAttrData.getBgColorMode(), Attributes.CM_P256);
+      assert.equal(term.curAttrData.getBgColor(), 255);
+    });
+    it('colormode transition 256 to 16', () => {
+      // enter 256 for FG and BG
+      term.writeSync(`\x1b[38;5;255;48;5;255m`);
+      // enter 16 for FG and BG
+      term.writeSync(`\x1b[37;47m`);
+      assert.equal(term.curAttrData.getFgColorMode(), Attributes.CM_P16);
+      assert.equal(term.curAttrData.getFgColor(), 7);
+      assert.equal(term.curAttrData.getBgColorMode(), Attributes.CM_P16);
+      assert.equal(term.curAttrData.getBgColor(), 7);
+    });
     it('should zero missing RGB values', () => {
       term.writeSync(`\x1b[38;2;1;2;3m`);
       term.writeSync(`\x1b[38;2;5m`);
diff --git a/src/InputHandler.ts b/src/InputHandler.ts
index ac4bee9363..94c7e96b2b 100644
--- a/src/InputHandler.ts
+++ b/src/InputHandler.ts
@@ -1693,7 +1693,7 @@ export class InputHandler extends Disposable implements IInputHandler {
         attr.bg &= ~(Attributes.CM_MASK | Attributes.RGB_MASK);
         attr.bg |= DEFAULT_ATTR_DATA.bg & (Attributes.PCOLOR_MASK | Attributes.RGB_MASK);
       } else if (p === 38) {
-        // fg color 256
+        // fg color 256 and RGB
         if (params[i + 1] === 2) {
           i += 2;
           attr.fg |= Attributes.CM_RGB;
@@ -1703,11 +1703,11 @@ export class InputHandler extends Disposable implements IInputHandler {
         } else if (params[i + 1] === 5) {
           i += 2;
           p = params[i] & 0xff;
-          attr.fg &= ~Attributes.PCOLOR_MASK;
+          attr.fg &= ~(Attributes.CM_MASK | Attributes.PCOLOR_MASK);
           attr.fg |= Attributes.CM_P256 | p;
         }
       } else if (p === 48) {
-        // bg color 256
+        // bg color 256 and RGB
         if (params[i + 1] === 2) {
           i += 2;
           attr.bg |= Attributes.CM_RGB;
@@ -1717,7 +1717,7 @@ export class InputHandler extends Disposable implements IInputHandler {
         } else if (params[i + 1] === 5) {
           i += 2;
           p = params[i] & 0xff;
-          attr.bg &= ~Attributes.PCOLOR_MASK;
+          attr.bg &= ~(Attributes.CM_MASK | Attributes.PCOLOR_MASK);
           attr.bg |= Attributes.CM_P256 | p;
         }
       } else if (p === 100) {