7 files changed, 19 insertions, 14 deletions
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index b1100a662357..efcb438766a9 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -968,7 +968,7 @@ void ExprConcatStrings::eval(EvalState & state, Env & env, Value & v)
 {
     PathSet context;
     std::ostringstream s;
-    int n = 0;
+    NixInt n = 0;
 
     bool first = true;
     ValueType firstType;
@@ -1021,7 +1021,7 @@ void EvalState::strictForceValue(Value & v)
 }
 
 
-int EvalState::forceInt(Value & v)
+NixInt EvalState::forceInt(Value & v)
 {
     forceValue(v);
     if (v.type != tInt)
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 5e98f5404b22..9717fb66d95d 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -159,7 +159,7 @@ public:
     void strictForceValue(Value & v);
 
     /* Force `v', and then verify that it has the expected type. */
-    int forceInt(Value & v);
+    NixInt forceInt(Value & v);
     bool forceBool(Value & v);
     inline void forceAttrs(Value & v);
     inline void forceList(Value & v);
diff --git a/src/libexpr/lexer.l b/src/libexpr/lexer.l
index 3b7c6bb57a06..76cd372013a5 100644
--- a/src/libexpr/lexer.l
+++ b/src/libexpr/lexer.l
@@ -110,8 +110,10 @@ or          { return OR_KW; }
 \+\+        { return CONCAT; }
 
 {ID}        { yylval->id = strdup(yytext); return ID; }
-{INT}       { int n = atoi(yytext); /* !!! overflow */
-              yylval->n = n;
+{INT}       { errno = 0;
+              yylval->n = strtol(yytext, 0, 10);
+              if (errno != 0)
+                  throw ParseError(format("invalid integer `%1%'") % yytext);
               return INT;
             }
 
diff --git a/src/libexpr/nixexpr.hh b/src/libexpr/nixexpr.hh
index 8256605b5cac..f6dcb3935752 100644
--- a/src/libexpr/nixexpr.hh
+++ b/src/libexpr/nixexpr.hh
@@ -75,9 +75,9 @@ std::ostream & operator << (std::ostream & str, Expr & e);
 
 struct ExprInt : Expr
 {
-    int n;
+    NixInt n;
     Value v;
-    ExprInt(int n) : n(n) { mkInt(v, n); };
+    ExprInt(NixInt n) : n(n) { mkInt(v, n); };
     COMMON_METHODS
     Value * maybeThunk(EvalState & state, Env & env);
 };
diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y
index cd1b0e21fa7c..7690271a86d3 100644
--- a/src/libexpr/parser.y
+++ b/src/libexpr/parser.y
@@ -238,7 +238,7 @@ void yyerror(YYLTYPE * loc, yyscan_t scanner, ParseData * data, const char * err
   nix::ExprAttrs * attrs;
   nix::Formals * formals;
   nix::Formal * formal;
-  int n;
+  nix::NixInt n;
   char * id; // !!! -> Symbol
   char * path;
   char * uri;
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 149c7ca399b1..deb66fd69f16 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -1024,7 +1024,7 @@ static void prim_mul(EvalState & state, Value * * args, Value & v)
 
 static void prim_div(EvalState & state, Value * * args, Value & v)
 {
-    int i2 = state.forceInt(*args[1]);
+    NixInt i2 = state.forceInt(*args[1]);
     if (i2 == 0) throw EvalError("division by zero");
     mkInt(v, state.forceInt(*args[0]) / i2);
 }
diff --git a/src/libexpr/value.hh b/src/libexpr/value.hh
index d49381a59165..ee5c7397b3a9 100644
--- a/src/libexpr/value.hh
+++ b/src/libexpr/value.hh
@@ -31,14 +31,17 @@ struct PrimOp;
 struct Symbol;
 
 
+typedef long NixInt;
+
+
 struct Value
 {
     ValueType type;
-    union 
+    union
     {
-        int integer;
+        NixInt integer;
         bool boolean;
-        
+
         /* Strings in the evaluator carry a so-called `context' which
            is a list of strings representing store paths.  This is to
            allow users to write things like
@@ -63,7 +66,7 @@ struct Value
             const char * s;
             const char * * context; // must be in sorted order
         } string;
-        
+
         const char * path;
         Bindings * attrs;
         struct {
@@ -97,7 +100,7 @@ static inline void clearValue(Value & v)
 }
 
 
-static inline void mkInt(Value & v, int n)
+static inline void mkInt(Value & v, NixInt n)
 {
     clearValue(v);
     v.type = tInt;