diff --git a/src/mathed/formulabase.C b/src/mathed/formulabase.C
index aed61cef26..99a653c03c 100644
--- a/src/mathed/formulabase.C
+++ b/src/mathed/formulabase.C
@@ -510,7 +510,7 @@ dispatch_result InsetFormulaBase::localDispatch(FuncRequest const & cmd)
 	}
 
 	case LFUN_PASTE: {
-		int n = 0;
+		size_t n = 0;
 		istringstream is(cmd.argument.c_str());
 		is >> n;
 		if (was_macro)
diff --git a/src/mathed/math_cursor.C b/src/mathed/math_cursor.C
index a8c143af4c..86ce84ce17 100644
--- a/src/mathed/math_cursor.C
+++ b/src/mathed/math_cursor.C
@@ -581,7 +581,7 @@ void MathCursor::selDel()
 }
 
 
-void MathCursor::selPaste(int n)
+void MathCursor::selPaste(size_t n)
 {
 	dump("selPaste");
 	selClearOrDel();
diff --git a/src/mathed/math_cursor.h b/src/mathed/math_cursor.h
index 08a019d0ae..e3f35b6578 100644
--- a/src/mathed/math_cursor.h
+++ b/src/mathed/math_cursor.h
@@ -152,7 +152,7 @@ public:
 	///
 	void selDel();
 	/// pastes n-th element of cut buffer
-	void selPaste(int n);
+	void selPaste(size_t n);
 	///
 	void selHandle(bool);
 	///
diff --git a/src/mathed/math_parser.C b/src/mathed/math_parser.C
index cc098d3ec6..9ef17d6d32 100644
--- a/src/mathed/math_parser.C
+++ b/src/mathed/math_parser.C
@@ -151,21 +151,21 @@ void catInit()
 	fill(theCatcode + 'a', theCatcode + 'z' + 1, catLetter);
 	fill(theCatcode + 'A', theCatcode + 'Z' + 1, catLetter);
 
-	theCatcode['\\'] = catEscape;
-	theCatcode['{']  = catBegin;
-	theCatcode['}']  = catEnd;
-	theCatcode['$']  = catMath;
-	theCatcode['&']  = catAlign;
-	theCatcode['\n'] = catNewline;
-	theCatcode['#']  = catParameter;
-	theCatcode['^']  = catSuper;
-	theCatcode['_']  = catSub;
-	theCatcode[''] = catIgnore;
-	theCatcode[' ']  = catSpace;
-	theCatcode['\t'] = catSpace;
-	theCatcode['\r'] = catNewline;
-	theCatcode['~']  = catActive;
-	theCatcode['%']  = catComment;
+	theCatcode[int('\\')] = catEscape;
+	theCatcode[int('{')]  = catBegin;
+	theCatcode[int('}')]  = catEnd;
+	theCatcode[int('$')]  = catMath;
+	theCatcode[int('&')]  = catAlign;
+	theCatcode[int('\n')] = catNewline;
+	theCatcode[int('#')]  = catParameter;
+	theCatcode[int('^')]  = catSuper;
+	theCatcode[int('_')]  = catSub;
+	theCatcode[int('')] = catIgnore;
+	theCatcode[int(' ')]  = catSpace;
+	theCatcode[int('\t')] = catSpace;
+	theCatcode[int('\r')] = catNewline;
+	theCatcode[int('~')]  = catActive;
+	theCatcode[int('%')]  = catComment;
 }