diff --git a/miscmaths.cc b/miscmaths.cc
index 6e42bd39774038a9ddefc25eee381b5e6df229ca..1b1b63944ee75425e2a673af899992f0383fcfdb 100644
--- a/miscmaths.cc
+++ b/miscmaths.cc
@@ -28,6 +28,15 @@ namespace MISCMATHS {
   using std::atan2;
 
 
+  string size(const Matrix& mat)
+  {
+    string str = num2str(mat.Nrows())+"*"+num2str(mat.Ncols());
+        
+    return str;
+  }
+
+
+
   float Sinc(const float x) {
     if (fabs(x)<1e-9) {
       return 1-x*x*M_PI*M_PI/6.0;
diff --git a/miscmaths.h b/miscmaths.h
index 963c20aae5b99217bb1916f1f9344918697241e4..0da285d5b0a1ea0141c2819303b45d0f5d2adaee 100644
--- a/miscmaths.h
+++ b/miscmaths.h
@@ -41,13 +41,7 @@ namespace MISCMATHS {
   // IO/string stuff
   template <class T> string num2str(T n, int width=-1);
 
-  string size(const Matrix& mat)
-  {
-    string str = num2str(mat.Nrows())+"*"+num2str(mat.Ncols());
-        
-    return str;
-  }
-
+  string size(const Matrix& mat);
   bool isnum(const string& str);
   ReturnMatrix read_ascii_matrix(const string& filename, int nrows, int ncols);
   ReturnMatrix read_ascii_matrix(int nrows, int ncols, const string& filename);