diff --git a/NEWS.md b/NEWS.md
index 3b3f52d7..1f620bd8 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -4,6 +4,7 @@ Red Panda C++ Version 2.20
   - fix: Projects created by some templates are not correct when editor's default encoding is not utf8.
   - fix: File/Project visit histories are not correctly saved when clearing.
   - change: Default max function frame size is 2MB under windows / 8MB others.
+  - fix: Octal numeric escape sequences is not correctly syntax highlighted.
 
 Red Panda C++ Version 2.19
 
diff --git a/libs/qsynedit/qsynedit/syntaxer/cpp.cpp b/libs/qsynedit/qsynedit/syntaxer/cpp.cpp
index 41882f79..5080d909 100644
--- a/libs/qsynedit/qsynedit/syntaxer/cpp.cpp
+++ b/libs/qsynedit/qsynedit/syntaxer/cpp.cpp
@@ -1177,7 +1177,13 @@ void CppSyntaxer::procStringEscapeSeq()
         case '5':
         case '6':
         case '7':
-            mRun+=3;
+            for (int i=0;i<3;i++) {
+                if (mRun>=mLineSize ||
+                   (mLine[mRun]<'0' || mLine[mRun]>'7')
+                   )
+                    break;
+                mRun+=1;
+            }
             break;
         case '8':
         case '9':
@@ -1194,6 +1200,14 @@ void CppSyntaxer::procStringEscapeSeq()
                 mRun+=1;
             }
             break;
+        case 'o':
+            mRun+=1;
+            while (mRun<mLineSize && (
+                   (mLine[mRun]>='0' && mLine[mRun]<='7')
+                   ))  {
+                mRun+=1;
+            }
+            break;
         case 'u':
             mRun+=5;
             break;