diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 50712a7251..9fbab559ea 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -146,12 +146,7 @@ static void processBinding(EvalState & state, Expr e, Derivation & drv,
     else if (matchUri(e, s)) ss.push_back(aterm2String(s));
     else if (e == eTrue) ss.push_back("1");
     else if (e == eFalse) ss.push_back("");
-
-    else if (matchInt(e, n)) {
-        ostringstream st;
-        st << n;
-        ss.push_back(st.str());
-    }
+    else if (matchInt(e, n)) ss.push_back(int2String(n));
 
     else if (matchAttrs(e, es)) {
         Expr a = queryAttr(e, "type");
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index f34bd9e059..02745498f9 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -360,10 +360,7 @@ Nest::~Nest()
 
 static string escVerbosity(Verbosity level)
 {
-    int l = (int) level;
-    ostringstream st;
-    st << l;
-    return st.str();
+    return int2String((int) level);
 }
 
 
@@ -829,6 +826,14 @@ bool statusOk(int status)
 }
 
 
+string int2String(int n)
+{
+    ostringstream str;
+    str << n;
+    return str.str();
+}
+
+
 bool string2Int(const string & s, int & n)
 {
     istringstream str(s);
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index fcf995af8a..22e614d958 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -292,6 +292,7 @@ bool statusOk(int status);
 
 
 /* Parse a string into an integer. */
+string int2String(int n);
 bool string2Int(const string & s, int & n);