diff --git a/src/mathed/InsetMathChar.cpp b/src/mathed/InsetMathChar.cpp
index a2b9b76069..1fef2209a5 100644
--- a/src/mathed/InsetMathChar.cpp
+++ b/src/mathed/InsetMathChar.cpp
@@ -109,7 +109,7 @@ void InsetMathChar::metrics(MetricsInfo & mi, Dimension & dim) const
 	if (mathfont && subst_) {
 		// If the char has a substitute, draw the replacement symbol
 		// instead, but only in math mode.
-		mathedSymbolDim(mi, dim, subst_);
+		mathedSymbolDim(mi.base, dim, subst_);
 		kerning_ = mathed_char_kerning(mi.base.font, *subst_->draw.rbegin());
 		return;
 	} else if (!slanted(char_) && mi.base.fontname == "mathnormal") {
diff --git a/src/mathed/InsetMathSymbol.cpp b/src/mathed/InsetMathSymbol.cpp
index 885aa60f01..92d2573560 100644
--- a/src/mathed/InsetMathSymbol.cpp
+++ b/src/mathed/InsetMathSymbol.cpp
@@ -61,7 +61,7 @@ docstring InsetMathSymbol::name() const
 void InsetMathSymbol::metrics(MetricsInfo & mi, Dimension & dim) const
 {
 	// set dim
-	mathedSymbolDim(mi, dim, sym_);
+	mathedSymbolDim(mi.base, dim, sym_);
 	// set kerning_
 	kerning_ = mathed_char_kerning(mi.base.font, *sym_->draw.rbegin());
 	// correct height for broken cmex and wasy font
diff --git a/src/mathed/MathSupport.cpp b/src/mathed/MathSupport.cpp
index 3d708406d3..16fbbcd4be 100644
--- a/src/mathed/MathSupport.cpp
+++ b/src/mathed/MathSupport.cpp
@@ -660,7 +660,7 @@ void mathed_draw_deco(PainterInfo & pi, int x, int y, int w, int h,
 }
 
 
-void mathedSymbolDim(MetricsInfo & mi, Dimension & dim, latexkeys const * sym)
+void mathedSymbolDim(MetricsBase & mb, Dimension & dim, latexkeys const * sym)
 {
 	LASSERT((bool)sym, return);
 	//lyxerr << "metrics: symbol: '" << sym->name
@@ -670,10 +670,10 @@ void mathedSymbolDim(MetricsInfo & mi, Dimension & dim, latexkeys const * sym)
 
 	bool const italic_upcase_greek = sym->inset == "cmr" &&
 		sym->extra == "mathalpha" &&
-		mi.base.fontname == "mathit";
+		mb.fontname == "mathit";
 	std::string const font = italic_upcase_greek ? "cmm" : sym->inset;
-	Changer dummy = mi.base.changeFontSet(font);
-	mathed_string_dim(mi.base.font, sym->draw, dim);
+	Changer dummy = mb.changeFontSet(font);
+	mathed_string_dim(mb.font, sym->draw, dim);
 }
 
 
diff --git a/src/mathed/MathSupport.h b/src/mathed/MathSupport.h
index 003631b8ae..b7e3c7c39b 100644
--- a/src/mathed/MathSupport.h
+++ b/src/mathed/MathSupport.h
@@ -18,6 +18,7 @@
 
 namespace lyx {
 
+class MetricsBase;
 class MetricsInfo;
 class PainterInfo;
 class FontInfo;
@@ -49,7 +50,7 @@ void mathed_string_dim(FontInfo const & font,
 
 int mathed_string_width(FontInfo const &, docstring const & s);
 
-void mathedSymbolDim(MetricsInfo & mi, Dimension & dim, latexkeys const * sym);
+void mathedSymbolDim(MetricsBase & mb, Dimension & dim, latexkeys const * sym);
 
 void mathedSymbolDraw(PainterInfo & pi, int x, int y, latexkeys const * sym);