diff --git a/src/libexpr/value.hh b/src/libexpr/value.hh
index 88424106c..62bdd9281 100644
--- a/src/libexpr/value.hh
+++ b/src/libexpr/value.hh
@@ -39,7 +39,7 @@ class XMLWriter;
 
 
 typedef long NixInt;
-typedef double NixFloat;
+typedef float NixFloat;
 
 /* External values must descend from ExternalValueBase, so that
  * type-agnostic nix functions (e.g. showType) can be implemented
diff --git a/src/libmain/shared.hh b/src/libmain/shared.hh
index a350f496d..32183d6a6 100644
--- a/src/libmain/shared.hh
+++ b/src/libmain/shared.hh
@@ -66,29 +66,6 @@ template<class N> N getIntArg(const string & opt,
     return n * multiplier;
 }
 
-template<class N> N getFloatArg(const string & opt,
-    Strings::iterator & i, const Strings::iterator & end, bool allowUnit)
-{
-    ++i;
-    if (i == end) throw UsageError(format("‘%1%’ requires an argument") % opt);
-    string s = *i;
-    N multiplier = 1;
-    if (allowUnit && !s.empty()) {
-        char u = std::toupper(*s.rbegin());
-        if (std::isalpha(u)) {
-            if (u == 'K') multiplier = 1ULL << 10;
-            else if (u == 'M') multiplier = 1ULL << 20;
-            else if (u == 'G') multiplier = 1ULL << 30;
-            else if (u == 'T') multiplier = 1ULL << 40;
-            else throw UsageError(format("invalid unit specifier ‘%1%’") % u);
-            s.resize(s.size() - 1);
-        }
-    }
-    N n;
-    if (!string2Float(s, n))
-        throw UsageError(format("‘%1%’ requires a float argument") % opt);
-    return n * multiplier;
-}
 
 /* Show the manual page for the specified program. */
 void showManPage(const string & name);