diff --git a/src/mathed/InsetMath.h b/src/mathed/InsetMath.h
index b23ffb5179..088fce6c2b 100644
--- a/src/mathed/InsetMath.h
+++ b/src/mathed/InsetMath.h
@@ -162,8 +162,12 @@ public:
 
 	/// identifies things that can get scripts
 	virtual bool isScriptable() const { return false; }
-	/// is the a relational operator (used for splitting equations)
-	virtual bool isRelOp() const { return false; }
+	/// identifies a binary operators (used for spacing)
+	virtual bool isMathBin() const { return false; }
+	/// identifies relational operators (used for spacing and splitting equations)
+	virtual bool isMathRel() const { return false; }
+	/// identifies punctuation (used for spacing)
+	virtual bool isMathPunct() const { return false; }
 	/// will this get written as a single block in {..}
 	virtual bool extraBraces() const { return false; }
 
diff --git a/src/mathed/InsetMathChar.cpp b/src/mathed/InsetMathChar.cpp
index 713e1353e6..2879ac91fc 100644
--- a/src/mathed/InsetMathChar.cpp
+++ b/src/mathed/InsetMathChar.cpp
@@ -26,7 +26,6 @@
 
 #include "support/debug.h"
 #include "support/lstrings.h"
-#include "support/lyxlib.h"
 #include "support/textutils.h"
 
 
@@ -35,12 +34,6 @@ namespace lyx {
 extern bool has_math_fonts;
 
 
-static bool isBinaryOp(char_type c)
-{
-	return support::contains("+-<>=/*", static_cast<char>(c));
-}
-
-
 static bool slanted(char_type c)
 {
 	return isAlphaASCII(c) || Encodings::isMathAlpha(c);
@@ -76,11 +69,15 @@ void InsetMathChar::metrics(MetricsInfo & mi, Dimension & dim) const
 		dim = fm.dimension(char_);
 		kerning_ = fm.rbearing(char_) - dim.wid;
 	}
-	int const em = mathed_font_em(mi.base.font);
-	if (isBinaryOp(char_))
-		dim.wid += support::iround(0.5 * em);
+	if (isMathBin())
+		dim.wid += 2 * mathed_medmuskip(mi.base.font);
+	else if (isMathRel())
+		dim.wid += 2 * mathed_thickmuskip(mi.base.font);
+	else if (isMathPunct())
+		dim.wid += mathed_thinmuskip(mi.base.font);
 	else if (char_ == '\'')
-		dim.wid += support::iround(0.1667 * em);
+		// FIXME: don't know where this is coming from
+		dim.wid += mathed_thinmuskip(mi.base.font);
 #else
 	whichFont(font_, code_, mi);
 	dim = theFontMetrics(font_).dimension(char_);
@@ -94,11 +91,12 @@ void InsetMathChar::metrics(MetricsInfo & mi, Dimension & dim) const
 void InsetMathChar::draw(PainterInfo & pi, int x, int y) const
 {
 	//lyxerr << "drawing '" << char_ << "' font: " << pi.base.fontname << std::endl;
-	int const em = mathed_font_em(pi.base.font);
-	if (isBinaryOp(char_))
-		x += support::iround(0.25 * em);
+	if (isMathBin())
+		x += mathed_medmuskip(pi.base.font);
+	else if (isMathRel())
+		x += mathed_thickmuskip(pi.base.font);
 	else if (char_ == '\'')
-		x += support::iround(0.0833 * em);
+		x += mathed_thinmuskip(pi.base.font) / 2;
 #if 1
 	if (char_ == '=' && has_math_fonts) {
 		FontSetChanger dummy(pi.base, "cmr");
@@ -237,9 +235,21 @@ void InsetMathChar::htmlize(HtmlStream & ms) const
 }
 
 
-bool InsetMathChar::isRelOp() const
+bool InsetMathChar::isMathBin() const
 {
-	return char_ == '=' || char_ == '<' || char_ == '>';
+	return support::contains("+-*", static_cast<char>(char_));
+}
+
+
+bool InsetMathChar::isMathRel() const
+{
+	return support::contains("<>=:", static_cast<char>(char_));
+}
+
+
+bool InsetMathChar::isMathPunct() const
+{
+	return support::contains(",;", static_cast<char>(char_));
 }
 
 
diff --git a/src/mathed/InsetMathChar.h b/src/mathed/InsetMathChar.h
index 65fac82fff..67bbc64e8c 100644
--- a/src/mathed/InsetMathChar.h
+++ b/src/mathed/InsetMathChar.h
@@ -49,7 +49,11 @@ public:
 	///
 	char_type getChar() const { return char_; }
 	///
-	bool isRelOp() const;
+	bool isMathBin() const;
+	///
+	bool isMathRel() const;
+	///
+	bool isMathPunct() const;
 	///
 	InsetCode lyxCode() const { return MATH_CHAR_CODE; }
 
diff --git a/src/mathed/InsetMathDelim.cpp b/src/mathed/InsetMathDelim.cpp
index 8e8b6e295b..b10d37ad69 100644
--- a/src/mathed/InsetMathDelim.cpp
+++ b/src/mathed/InsetMathDelim.cpp
@@ -115,7 +115,7 @@ void InsetMathDelim::metrics(MetricsInfo & mi, Dimension & dim) const
 		dw_ = 8;
 	if (dw_ < 4)
 		dw_ = 4;
-	dim.wid = dim0.width() + 2 * dw_ + 8;
+	dim.wid = dim0.width() + 2 * dw_ + 2 * mathed_thinmuskip(mi.base.font);
 	dim.asc = max(a0, d0) + h0;
 	dim.des = max(a0, d0) - h0;
 }
@@ -125,9 +125,10 @@ void InsetMathDelim::draw(PainterInfo & pi, int x, int y) const
 {
 	Dimension const dim = dimension(*pi.base.bv);
 	int const b = y - dim.asc;
-	cell(0).draw(pi, x + dw_ + 4, y);
-	mathed_draw_deco(pi, x + 4, b, dw_, dim.height(), left_);
-	mathed_draw_deco(pi, x + dim.width() - dw_ - 4,
+	int const skip = mathed_thinmuskip(pi.base.font);
+	cell(0).draw(pi, x + dw_ + skip, y);
+	mathed_draw_deco(pi, x + skip, b, dw_, dim.height(), left_);
+	mathed_draw_deco(pi, x + dim.width() - dw_ - skip,
 		b, dw_, dim.height(), right_);
 	setPosCache(pi, x, y);
 }
diff --git a/src/mathed/InsetMathHull.cpp b/src/mathed/InsetMathHull.cpp
index 48792a81ae..34955147e2 100644
--- a/src/mathed/InsetMathHull.cpp
+++ b/src/mathed/InsetMathHull.cpp
@@ -106,7 +106,7 @@ namespace {
 	size_t firstRelOp(MathData const & ar)
 	{
 		for (MathData::const_iterator it = ar.begin(); it != ar.end(); ++it)
-			if ((*it)->isRelOp())
+			if ((*it)->isMathRel())
 				return it - ar.begin();
 		return ar.size();
 	}
diff --git a/src/mathed/InsetMathSymbol.cpp b/src/mathed/InsetMathSymbol.cpp
index a160dec684..a04f6e0bcf 100644
--- a/src/mathed/InsetMathSymbol.cpp
+++ b/src/mathed/InsetMathSymbol.cpp
@@ -21,7 +21,6 @@
 
 #include "support/debug.h"
 #include "support/docstream.h"
-#include "support/lyxlib.h"
 #include "support/textutils.h"
 
 #include <boost/scoped_ptr.hpp>
@@ -68,7 +67,6 @@ void InsetMathSymbol::metrics(MetricsInfo & mi, Dimension & dim) const
 					 sym_->extra == "mathalpha" &&
 					 mi.base.fontname == "mathit";
 	std::string const font = italic_upcase_greek ? "cmm" : sym_->inset;
-	int const em = mathed_font_em(mi.base.font);
 	FontSetChanger dummy(mi.base, from_ascii(font));
 	mathed_string_dim(mi.base.font, sym_->draw, dim);
 	docstring::const_reverse_iterator rit = sym_->draw.rbegin();
@@ -80,10 +78,15 @@ void InsetMathSymbol::metrics(MetricsInfo & mi, Dimension & dim) const
 		dim.des -= h_;
 	}
 	// seperate things a bit
-	if (isRelOp())
-		dim.wid += support::iround(0.5 * em);
-	else
-		dim.wid += support::iround(0.1667 * em);
+	if (isMathBin())
+		dim.wid += 2 * mathed_medmuskip(mi.base.font);
+	else if (isMathRel())
+		dim.wid += 2 * mathed_thickmuskip(mi.base.font);
+	else if (isMathPunct())
+		dim.wid += mathed_thinmuskip(mi.base.font);
+	// FIXME: I see no reason for this
+	//else
+	//	dim.wid += support::iround(0.1667 * em);
 
 	scriptable_ = false;
 	if (mi.base.style == LM_ST_DISPLAY)
@@ -105,11 +108,13 @@ void InsetMathSymbol::draw(PainterInfo & pi, int x, int y) const
 					 sym_->extra == "mathalpha" &&
 					 pi.base.fontname == "mathit";
 	std::string const font = italic_upcase_greek ? "cmm" : sym_->inset;
-	int const em = mathed_font_em(pi.base.font);
-	if (isRelOp())
-		x += support::iround(0.25 * em);
-	else
-		x += support::iround(0.0833 * em);
+	if (isMathBin())
+		x += mathed_medmuskip(pi.base.font);
+	else if (isMathRel())
+		x += mathed_thickmuskip(pi.base.font);
+	// FIXME: I see no reason for this
+	//else
+	//	x += support::iround(0.0833 * em);
 
 	FontSetChanger dummy(pi.base, from_ascii(font));
 	pi.draw(x, y - h_, sym_->draw);
@@ -122,12 +127,24 @@ InsetMath::mode_type InsetMathSymbol::currentMode() const
 }
 
 
-bool InsetMathSymbol::isRelOp() const
+bool InsetMathSymbol::isMathBin() const
+{
+	return sym_->extra == "mathbin";
+}
+
+
+bool InsetMathSymbol::isMathRel() const
 {
 	return sym_->extra == "mathrel";
 }
 
 
+bool InsetMathSymbol::isMathPunct() const
+{
+	return sym_->extra == "mathpunct";
+}
+
+
 bool InsetMathSymbol::isOrdAlpha() const
 {
 	return sym_->extra == "mathord" || sym_->extra == "mathalpha";
diff --git a/src/mathed/InsetMathSymbol.h b/src/mathed/InsetMathSymbol.h
index bb18217a84..6ca3ded7d1 100644
--- a/src/mathed/InsetMathSymbol.h
+++ b/src/mathed/InsetMathSymbol.h
@@ -40,7 +40,11 @@ public:
 	///
 	mode_type currentMode() const;
 	///
-	bool isRelOp() const;
+	bool isMathRel() const;
+	///
+	bool isMathBin() const;
+	///
+	bool isMathPunct() const;
 	///
 	bool isOrdAlpha() const;
 	/// do we take scripts?
diff --git a/src/mathed/MathSupport.cpp b/src/mathed/MathSupport.cpp
index 9801151129..7769176e7a 100644
--- a/src/mathed/MathSupport.cpp
+++ b/src/mathed/MathSupport.cpp
@@ -25,6 +25,7 @@
 
 #include "support/debug.h"
 #include "support/docstream.h"
+#include "support/lyxlib.h"
 
 #include <map>
 #include <algorithm>
@@ -506,6 +507,46 @@ int mathed_font_em(FontInfo const & font)
 	return theFontMetrics(font).em();
 }
 
+/* The math units. Quoting TeX by Topic, p.205:
+ *
+ * Spacing around mathematical objects is measured in mu units. A mu
+ * is 1/18th part of \fontdimen6 of the font in family 2 in the
+ * current style, the ‘quad’ value of the symbol font.
+ *
+ * A \thickmuskip (default value in plain TeX: 5mu plus 5mu) is
+ * inserted around (binary) relations, except where these are preceded
+ * or followed by other relations or punctuation, and except if they
+ * follow an open, or precede a close symbol.
+ *
+ * A \medmuskip (default value in plain TeX: 4mu plus 2mu minus 4mu)
+ * is put around binary operators.
+ *
+ * A \thinmuskip (default value in plain TeX: 3mu) follows after
+ * punctuation, and is put around inner objects, except where these
+ * are followed by a close or preceded by an open symbol, and except
+ * if the other object is a large operator or a binary relation.
+ */
+
+int mathed_thinmuskip(FontInfo font)
+{
+	font.setFamily(SYMBOL_FAMILY);
+	return support::iround(3.0 / 18 * theFontMetrics(font).em());
+}
+
+
+int mathed_medmuskip(FontInfo font)
+{
+	font.setFamily(SYMBOL_FAMILY);
+	return support::iround(4.0 / 18 * theFontMetrics(font).em());
+}
+
+
+int mathed_thickmuskip(FontInfo font)
+{
+	font.setFamily(SYMBOL_FAMILY);
+	return support::iround(5.0 / 18 * theFontMetrics(font).em());
+}
+
 
 int mathed_char_width(FontInfo const & font, char_type c)
 {
diff --git a/src/mathed/MathSupport.h b/src/mathed/MathSupport.h
index aa5ef2adc2..c14f21a807 100644
--- a/src/mathed/MathSupport.h
+++ b/src/mathed/MathSupport.h
@@ -29,6 +29,12 @@ class InsetMath;
 
 int mathed_font_em(FontInfo const &);
 
+int mathed_thinmuskip(FontInfo font);
+
+int mathed_medmuskip(FontInfo font);
+
+int mathed_thickmuskip(FontInfo font);
+
 int mathed_char_width(FontInfo const &, char_type c);
 
 int mathed_char_kerning(FontInfo const &, char_type c);