diff --git a/src/Notepad3.c b/src/Notepad3.c
index 4d3757d90..610807a11 100644
--- a/src/Notepad3.c
+++ b/src/Notepad3.c
@@ -2520,6 +2520,9 @@ static void  _InitializeSciEditCtrl(HWND hwndEditCtrl)
     SciCall_SetMarginTypeN(MARGIN_SCI_FOLDING, SC_MARGIN_COLOUR);
     SciCall_SetMarginMaskN(MARGIN_SCI_FOLDING, SC_MASK_FOLDERS);
 
+    //~SciCall_SetMarginLeft(1); ~ set by STYLE_INDENTGUIDE
+    //~SciCall_SetMarginRight(1);
+
     SciCall_SetEOLMode(Settings.DefaultEOLMode);
     SciCall_SetPasteConvertEndings(true);
     SciCall_UsePopUp(SC_POPUP_TEXT);
diff --git a/src/SciCall.h b/src/SciCall.h
index 54d045ced..ec75f18d2 100644
--- a/src/SciCall.h
+++ b/src/SciCall.h
@@ -662,6 +662,8 @@ DeclareSciCallV2(SetMarginCursorN, SETMARGINCURSORN, uintptr_t, margin, int, cur
 DeclareSciCallV2(SetFoldMarginColour, SETFOLDMARGINCOLOUR, bool, useSetting, COLORREF, colour);
 DeclareSciCallV2(SetFoldMarginHiColour, SETFOLDMARGINHICOLOUR, bool, useSetting, COLORREF, colour);
 DeclareSciCallV01(SetDefaultFoldDisplayText, SETDEFAULTFOLDDISPLAYTEXT, const char*, text);
+DeclareSciCallV01(SetMarginLeft, SETMARGINLEFT, int, width);
+DeclareSciCallV01(SetMarginRight, SETMARGINRIGHT, int, width);
 
 DeclareSciCallR2(TextWidth, TEXTWIDTH, int, int, styleNumber, const char *, text);
 
diff --git a/src/Styles.c b/src/Styles.c
index 4c7f2c1c2..254ae7182 100644
--- a/src/Styles.c
+++ b/src/Styles.c
@@ -4100,9 +4100,17 @@ void Style_SetStyles(HWND hwnd, const int iStyle, LPCWSTR lpszStyle, const float
     }
 
     // Size values are relative to BaseFontSize/CurrentFontSize
-    float fFontSize = fBaseFontSize;
-    Style_StrGetSizeFloatEx(lpszStyle, &fFontSize);
-    SendMessage(hwnd, SCI_STYLESETSIZEFRACTIONAL, iStyle, f2int(fFontSize * SC_FONT_SIZE_MULTIPLIER));
+    if (iStyle != STYLE_INDENTGUIDE) {
+        float fFontSize = fBaseFontSize;
+        Style_StrGetSizeFloatEx(lpszStyle, &fFontSize);
+        SendMessage(hwnd, SCI_STYLESETSIZEFRACTIONAL, iStyle, f2int(fFontSize * SC_FONT_SIZE_MULTIPLIER));
+    }
+    else {
+        float fWidth = 1.0;
+        Style_StrGetSizeFloatEx(lpszStyle, &fWidth);
+        int const width = clampi(f2int(fWidth), 0, 256);
+        SciCall_SetMarginLeft(width);
+    }
 
     char localeNameA[LOCALE_NAME_MAX_LENGTH] = "en-us\0";
 #if defined(HAVE_DYN_LOAD_LIBS_MUI_LNGS)