diff --git a/maths.hpp b/maths.hpp
index 9f57d8ad..70999349 100644
--- a/maths.hpp
+++ b/maths.hpp
@@ -84,7 +84,7 @@ almost_equal (const double &a, const double &b);
 #pragma GCC diagnostic ignored "-Wfloat-equal"
 template <typename T>
 bool
-exact_equal (const T &a, const T &b) 
+exactly_equal (const T &a, const T &b) 
     { return a == b; }
 #pragma GCC diagnostic pop
 
diff --git a/matrix.cpp b/matrix.cpp
index f6e49aa7..9e7bec62 100644
--- a/matrix.cpp
+++ b/matrix.cpp
@@ -124,10 +124,10 @@ matrix::to_global (const util::point &p) const {
 
 bool
 matrix::is_affine (void) const {
-    return exact_equal (values[3][0], 0.0) &&
-           exact_equal (values[3][1], 0.0) &&
-           exact_equal (values[3][2], 0.0) &&
-           exact_equal (values[3][3], 1.0);
+    return exactly_equal (values[3][0], 0.0) &&
+           exactly_equal (values[3][1], 0.0) &&
+           exactly_equal (values[3][2], 0.0) &&
+           exactly_equal (values[3][3], 1.0);
 }