diff --git a/src/libexpr/attr-set.cc b/src/libexpr/attr-set.cc
index b284daa3c..0474865c6 100644
--- a/src/libexpr/attr-set.cc
+++ b/src/libexpr/attr-set.cc
@@ -24,13 +24,15 @@ static void * allocBytes(size_t n)
 /* Allocate a new array of attributes for an attribute set with a specific
    capacity. The space is implicitly reserved after the Bindings
    structure. */
-Bindings * EvalState::allocBindings(Bindings::size_t capacity)
+Bindings * EvalState::allocBindings(size_t capacity)
 {
-    return new (allocBytes(sizeof(Bindings) + sizeof(Attr) * capacity)) Bindings(capacity);
+    if (capacity > std::numeric_limits<Bindings::size_t>::max())
+        throw Error("attribute set of size %d is too big", capacity);
+    return new (allocBytes(sizeof(Bindings) + sizeof(Attr) * capacity)) Bindings((Bindings::size_t) capacity);
 }
 
 
-void EvalState::mkAttrs(Value & v, unsigned int capacity)
+void EvalState::mkAttrs(Value & v, size_t capacity)
 {
     if (capacity == 0) {
         v = vEmptySet;
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 854899079..a2cce162b 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -422,7 +422,7 @@ Value * EvalState::addConstant(const string & name, Value & v)
 
 
 Value * EvalState::addPrimOp(const string & name,
-    unsigned int arity, PrimOpFun primOp)
+    size_t arity, PrimOpFun primOp)
 {
     if (arity == 0) {
         Value v;
@@ -528,7 +528,7 @@ Value & mkString(Value & v, const string & s, const PathSet & context)
 {
     mkString(v, s.c_str());
     if (!context.empty()) {
-        unsigned int n = 0;
+        size_t n = 0;
         v.string.context = (const char * *)
             allocBytes((context.size() + 1) * sizeof(char *));
         for (auto & i : context)
@@ -547,7 +547,7 @@ void mkPath(Value & v, const char * s)
 
 inline Value * EvalState::lookupVar(Env * env, const ExprVar & var, bool noEval)
 {
-    for (unsigned int l = var.level; l; --l, env = env->up) ;
+    for (size_t l = var.level; l; --l, env = env->up) ;
 
     if (!var.fromWith) return env->values[var.displ];
 
@@ -566,7 +566,7 @@ inline Value * EvalState::lookupVar(Env * env, const ExprVar & var, bool noEval)
         }
         if (!env->prevWith)
             throwUndefinedVarError("undefined variable '%1%' at %2%", var.name, var.pos);
-        for (unsigned int l = env->prevWith; l; --l, env = env->up) ;
+        for (size_t l = env->prevWith; l; --l, env = env->up) ;
     }
 }
 
@@ -578,14 +578,15 @@ Value * EvalState::allocValue()
 }
 
 
-Env & EvalState::allocEnv(unsigned int size)
+Env & EvalState::allocEnv(size_t size)
 {
-    assert(size <= std::numeric_limits<decltype(Env::size)>::max());
+    if (size > std::numeric_limits<decltype(Env::size)>::max())
+        throw Error("environment size %d is too big", size);
 
     nrEnvs++;
     nrValuesInEnvs += size;
     Env * env = (Env *) allocBytes(sizeof(Env) + size * sizeof(Value *));
-    env->size = size;
+    env->size = (decltype(Env::size)) size;
 
     /* We assume that env->values has been cleared by the allocator; maybeThunk() and lookupVar fromWith expect this. */
 
@@ -593,7 +594,7 @@ Env & EvalState::allocEnv(unsigned int size)
 }
 
 
-void EvalState::mkList(Value & v, unsigned int size)
+void EvalState::mkList(Value & v, size_t size)
 {
     clearValue(v);
     if (size == 1)
@@ -805,7 +806,7 @@ void ExprAttrs::eval(EvalState & state, Env & env, Value & v)
         /* The recursive attributes are evaluated in the new
            environment, while the inherited attributes are evaluated
            in the original environment. */
-        unsigned int displ = 0;
+        size_t displ = 0;
         for (auto & i : attrs) {
             Value * vAttr;
             if (hasOverrides && !i.second.inherited) {
@@ -879,7 +880,7 @@ void ExprLet::eval(EvalState & state, Env & env, Value & v)
     /* The recursive attributes are evaluated in the new environment,
        while the inherited attributes are evaluated in the original
        environment. */
-    unsigned int displ = 0;
+    size_t displ = 0;
     for (auto & i : attrs->attrs)
         env2.values[displ++] = i.second.e->maybeThunk(state, i.second.inherited ? env : env2);
 
@@ -890,7 +891,7 @@ void ExprLet::eval(EvalState & state, Env & env, Value & v)
 void ExprList::eval(EvalState & state, Env & env, Value & v)
 {
     state.mkList(v, elems.size());
-    for (unsigned int n = 0; n < elems.size(); ++n)
+    for (size_t n = 0; n < elems.size(); ++n)
         v.listElems()[n] = elems[n]->maybeThunk(state, env);
 }
 
@@ -1012,22 +1013,22 @@ void ExprApp::eval(EvalState & state, Env & env, Value & v)
 void EvalState::callPrimOp(Value & fun, Value & arg, Value & v, const Pos & pos)
 {
     /* Figure out the number of arguments still needed. */
-    unsigned int argsDone = 0;
+    size_t argsDone = 0;
     Value * primOp = &fun;
     while (primOp->type == tPrimOpApp) {
         argsDone++;
         primOp = primOp->primOpApp.left;
     }
     assert(primOp->type == tPrimOp);
-    unsigned int arity = primOp->primOp->arity;
-    unsigned int argsLeft = arity - argsDone;
+    auto arity = primOp->primOp->arity;
+    auto argsLeft = arity - argsDone;
 
     if (argsLeft == 1) {
         /* We have all the arguments, so call the primop. */
 
         /* Put all the arguments in an array. */
         Value * vArgs[arity];
-        unsigned int n = arity - 1;
+        auto n = arity - 1;
         vArgs[n--] = &arg;
         for (Value * arg = &fun; arg->type == tPrimOpApp; arg = arg->primOpApp.left)
             vArgs[n--] = arg->primOpApp.right;
@@ -1076,13 +1077,13 @@ void EvalState::callFunction(Value & fun, Value & arg, Value & v, const Pos & po
 
     ExprLambda & lambda(*fun.lambda.fun);
 
-    unsigned int size =
+    auto size =
         (lambda.arg.empty() ? 0 : 1) +
         (lambda.matchAttrs ? lambda.formals->formals.size() : 0);
     Env & env2(allocEnv(size));
     env2.up = fun.lambda.env;
 
-    unsigned int displ = 0;
+    size_t displ = 0;
 
     if (!lambda.matchAttrs)
         env2.values[displ++] = &arg;
@@ -1096,7 +1097,7 @@ void EvalState::callFunction(Value & fun, Value & arg, Value & v, const Pos & po
         /* For each formal argument, get the actual argument.  If
            there is no matching actual argument but the formal
            argument has a default, use the default. */
-        unsigned int attrsUsed = 0;
+        size_t attrsUsed = 0;
         for (auto & i : lambda.formals->formals) {
             Bindings::iterator j = arg.attrs->find(i.name);
             if (j == arg.attrs->end()) {
@@ -1294,15 +1295,15 @@ void ExprOpConcatLists::eval(EvalState & state, Env & env, Value & v)
 }
 
 
-void EvalState::concatLists(Value & v, unsigned int nrLists, Value * * lists, const Pos & pos)
+void EvalState::concatLists(Value & v, size_t nrLists, Value * * lists, const Pos & pos)
 {
     nrListConcats++;
 
     Value * nonEmpty = 0;
-    unsigned int len = 0;
-    for (unsigned int n = 0; n < nrLists; ++n) {
+    size_t len = 0;
+    for (size_t n = 0; n < nrLists; ++n) {
         forceList(*lists[n], pos);
-        unsigned int l = lists[n]->listSize();
+        auto l = lists[n]->listSize();
         len += l;
         if (l) nonEmpty = lists[n];
     }
@@ -1314,8 +1315,8 @@ void EvalState::concatLists(Value & v, unsigned int nrLists, Value * * lists, co
 
     mkList(v, len);
     auto out = v.listElems();
-    for (unsigned int n = 0, pos = 0; n < nrLists; ++n) {
-        unsigned int l = lists[n]->listSize();
+    for (size_t n = 0, pos = 0; n < nrLists; ++n) {
+        auto l = lists[n]->listSize();
         if (l)
             memcpy(out + pos, lists[n]->listElems(), l * sizeof(Value *));
         pos += l;
@@ -1410,7 +1411,7 @@ void EvalState::forceValueDeep(Value & v)
         }
 
         else if (v.isList()) {
-            for (unsigned int n = 0; n < v.listSize(); ++n)
+            for (size_t n = 0; n < v.listSize(); ++n)
                 recurse(*v.listElems()[n]);
         }
     };
@@ -1562,7 +1563,7 @@ string EvalState::coerceToString(const Pos & pos, Value & v, PathSet & context,
 
         if (v.isList()) {
             string result;
-            for (unsigned int n = 0; n < v.listSize(); ++n) {
+            for (size_t n = 0; n < v.listSize(); ++n) {
                 result += coerceToString(pos, *v.listElems()[n],
                     context, coerceMore, copyToStore);
                 if (n < v.listSize() - 1
@@ -1649,7 +1650,7 @@ bool EvalState::eqValues(Value & v1, Value & v2)
         case tList2:
         case tListN:
             if (v1.listSize() != v2.listSize()) return false;
-            for (unsigned int n = 0; n < v1.listSize(); ++n)
+            for (size_t n = 0; n < v1.listSize(); ++n)
                 if (!eqValues(*v1.listElems()[n], *v2.listElems()[n])) return false;
             return true;
 
@@ -1740,26 +1741,26 @@ void EvalState::printStats()
         v = lvlInfo;
 
         printMsg(v, format("calls to %1% primops:") % primOpCalls.size());
-        typedef std::multimap<unsigned int, Symbol> PrimOpCalls_;
+        typedef std::multimap<size_t, Symbol> PrimOpCalls_;
         PrimOpCalls_ primOpCalls_;
         for (auto & i : primOpCalls)
-            primOpCalls_.insert(std::pair<unsigned int, Symbol>(i.second, i.first));
+            primOpCalls_.insert(std::pair<size_t, Symbol>(i.second, i.first));
         for (auto i = primOpCalls_.rbegin(); i != primOpCalls_.rend(); ++i)
             printMsg(v, format("%1$10d %2%") % i->first % i->second);
 
         printMsg(v, format("calls to %1% functions:") % functionCalls.size());
-        typedef std::multimap<unsigned int, ExprLambda *> FunctionCalls_;
+        typedef std::multimap<size_t, ExprLambda *> FunctionCalls_;
         FunctionCalls_ functionCalls_;
         for (auto & i : functionCalls)
-            functionCalls_.insert(std::pair<unsigned int, ExprLambda *>(i.second, i.first));
+            functionCalls_.insert(std::pair<size_t, ExprLambda *>(i.second, i.first));
         for (auto i = functionCalls_.rbegin(); i != functionCalls_.rend(); ++i)
             printMsg(v, format("%1$10d %2%") % i->first % i->second->showNamePos());
 
         printMsg(v, format("evaluations of %1% attributes:") % attrSelects.size());
-        typedef std::multimap<unsigned int, Pos> AttrSelects_;
+        typedef std::multimap<size_t, Pos> AttrSelects_;
         AttrSelects_ attrSelects_;
         for (auto & i : attrSelects)
-            attrSelects_.insert(std::pair<unsigned int, Pos>(i.second, i.first));
+            attrSelects_.insert(std::pair<size_t, Pos>(i.second, i.first));
         for (auto i = attrSelects_.rbegin(); i != attrSelects_.rend(); ++i)
             printMsg(v, format("%1$10d %2%") % i->first % i->second);
 
@@ -1810,7 +1811,7 @@ size_t valueSize(Value & v)
             if (seen.find(v.listElems()) == seen.end()) {
                 seen.insert(v.listElems());
                 sz += v.listSize() * sizeof(Value *);
-                for (unsigned int n = 0; n < v.listSize(); ++n)
+                for (size_t n = 0; n < v.listSize(); ++n)
                     sz += doValue(*v.listElems()[n]);
             }
             break;
@@ -1846,7 +1847,7 @@ size_t valueSize(Value & v)
 
         size_t sz = sizeof(Env) + sizeof(Value *) * env.size;
 
-        for (unsigned int i = 0; i < env.size; ++i)
+        for (size_t i = 0; i < env.size; ++i)
             if (env.values[i])
                 sz += doValue(*env.values[i]);
 
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 9d8799b79..86e93a5ac 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -214,7 +214,7 @@ private:
     Value * addConstant(const string & name, Value & v);
 
     Value * addPrimOp(const string & name,
-        unsigned int arity, PrimOpFun primOp);
+        size_t arity, PrimOpFun primOp);
 
 public:
 
@@ -248,18 +248,18 @@ public:
 
     /* Allocation primitives. */
     Value * allocValue();
-    Env & allocEnv(unsigned int size);
+    Env & allocEnv(size_t size);
 
     Value * allocAttr(Value & vAttrs, const Symbol & name);
 
-    Bindings * allocBindings(Bindings::size_t capacity);
+    Bindings * allocBindings(size_t capacity);
 
-    void mkList(Value & v, unsigned int length);
-    void mkAttrs(Value & v, unsigned int capacity);
+    void mkList(Value & v, size_t length);
+    void mkAttrs(Value & v, size_t capacity);
     void mkThunk_(Value & v, Expr * expr);
     void mkPos(Value & v, Pos * pos);
 
-    void concatLists(Value & v, unsigned int nrLists, Value * * lists, const Pos & pos);
+    void concatLists(Value & v, size_t nrLists, Value * * lists, const Pos & pos);
 
     /* Print statistics. */
     void printStats();
@@ -282,15 +282,15 @@ private:
 
     bool countCalls;
 
-    typedef std::map<Symbol, unsigned int> PrimOpCalls;
+    typedef std::map<Symbol, size_t> PrimOpCalls;
     PrimOpCalls primOpCalls;
 
-    typedef std::map<ExprLambda *, unsigned int> FunctionCalls;
+    typedef std::map<ExprLambda *, size_t> FunctionCalls;
     FunctionCalls functionCalls;
 
     void incrFunctionCall(ExprLambda * fun);
 
-    typedef std::map<Pos, unsigned int> AttrSelects;
+    typedef std::map<Pos, size_t> AttrSelects;
     AttrSelects attrSelects;
 
     friend struct ExprOpUpdate;
diff --git a/src/libexpr/nixexpr.hh b/src/libexpr/nixexpr.hh
index 8c8f39640..b486595f0 100644
--- a/src/libexpr/nixexpr.hh
+++ b/src/libexpr/nixexpr.hh
@@ -255,7 +255,7 @@ struct ExprWith : Expr
 {
     Pos pos;
     Expr * attrs, * body;
-    unsigned int prevWith;
+    size_t prevWith;
     ExprWith(const Pos & pos, Expr * attrs, Expr * body) : pos(pos), attrs(attrs), body(body) { };
     COMMON_METHODS
 };
diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y
index ef11dd609..e3f452184 100644
--- a/src/libexpr/parser.y
+++ b/src/libexpr/parser.y
@@ -136,8 +136,8 @@ static Expr * stripIndentation(const Pos & pos, SymbolTable & symbols, vector<Ex
        whitespace-only final lines are not taken into account.  (So
        the " " in "\n ''" is ignored, but the " " in "\n foo''" is.) */
     bool atStartOfLine = true; /* = seen only whitespace in the current line */
-    unsigned int minIndent = 1000000;
-    unsigned int curIndent = 0;
+    size_t minIndent = 1000000;
+    size_t curIndent = 0;
     for (auto & i : es) {
         ExprIndStr * e = dynamic_cast<ExprIndStr *>(i);
         if (!e) {
@@ -148,7 +148,7 @@ static Expr * stripIndentation(const Pos & pos, SymbolTable & symbols, vector<Ex
             }
             continue;
         }
-        for (unsigned int j = 0; j < e->s.size(); ++j) {
+        for (size_t j = 0; j < e->s.size(); ++j) {
             if (atStartOfLine) {
                 if (e->s[j] == ' ')
                     curIndent++;
@@ -170,8 +170,8 @@ static Expr * stripIndentation(const Pos & pos, SymbolTable & symbols, vector<Ex
     /* Strip spaces from each line. */
     vector<Expr *> * es2 = new vector<Expr *>;
     atStartOfLine = true;
-    unsigned int curDropped = 0;
-    unsigned int n = es.size();
+    size_t curDropped = 0;
+    size_t n = es.size();
     for (vector<Expr *>::iterator i = es.begin(); i != es.end(); ++i, --n) {
         ExprIndStr * e = dynamic_cast<ExprIndStr *>(*i);
         if (!e) {
@@ -182,7 +182,7 @@ static Expr * stripIndentation(const Pos & pos, SymbolTable & symbols, vector<Ex
         }
 
         string s2;
-        for (unsigned int j = 0; j < e->s.size(); ++j) {
+        for (size_t j = 0; j < e->s.size(); ++j) {
             if (atStartOfLine) {
                 if (e->s[j] == ' ') {
                     if (curDropped++ >= minIndent)
diff --git a/src/libexpr/symbol-table.hh b/src/libexpr/symbol-table.hh
index c2ee49dd3..44929f7ee 100644
--- a/src/libexpr/symbol-table.hh
+++ b/src/libexpr/symbol-table.hh
@@ -69,7 +69,7 @@ public:
         return Symbol(&*res.first);
     }
 
-    unsigned int size() const
+    size_t size() const
     {
         return symbols.size();
     }
diff --git a/src/libexpr/value.hh b/src/libexpr/value.hh
index 9df516f06..66b41a158 100644
--- a/src/libexpr/value.hh
+++ b/src/libexpr/value.hh
@@ -128,7 +128,7 @@ struct Value
         const char * path;
         Bindings * attrs;
         struct {
-            unsigned int size;
+            size_t size;
             Value * * elems;
         } bigList;
         Value * smallList[2];
@@ -166,7 +166,7 @@ struct Value
         return type == tList1 || type == tList2 ? smallList : bigList.elems;
     }
 
-    unsigned int listSize() const
+    size_t listSize() const
     {
         return type == tList1 ? 1 : type == tList2 ? 2 : bigList.size;
     }
diff --git a/src/libmain/stack.cc b/src/libmain/stack.cc
index cc0eea68f..13896aeec 100644
--- a/src/libmain/stack.cc
+++ b/src/libmain/stack.cc
@@ -30,7 +30,7 @@ static void sigsegvHandler(int signo, siginfo_t * info, void * ctx)
         if (diff < 0) diff = -diff;
         if (diff < 4096) {
             char msg[] = "error: stack overflow (possible infinite recursion)\n";
-            [[gnu::unused]] int res = write(2, msg, strlen(msg));
+            [[gnu::unused]] auto res = write(2, msg, strlen(msg));
             _exit(1); // maybe abort instead?
         }
     }
diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index 610878544..a2b245240 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -842,9 +842,9 @@ private:
     BuildResult result;
 
     /* The current round, if we're building multiple times. */
-    unsigned int curRound = 1;
+    size_t curRound = 1;
 
-    unsigned int nrRounds;
+    size_t nrRounds;
 
     /* Path registration info from the previous round, if we're
        building multiple times. Since this contains the hash, it
@@ -1169,7 +1169,7 @@ void DerivationGoal::outputsSubstituted()
         return;
     }
 
-    unsigned int nrInvalid = checkPathValidity(false, buildMode == bmRepair).size();
+    auto nrInvalid = checkPathValidity(false, buildMode == bmRepair).size();
     if (buildMode == bmNormal && nrInvalid == 0) {
         done(BuildResult::Substituted);
         return;
diff --git a/src/libstore/references.cc b/src/libstore/references.cc
index ba9f18b9c..5b7eb1f84 100644
--- a/src/libstore/references.cc
+++ b/src/libstore/references.cc
@@ -13,7 +13,7 @@ namespace nix {
 static unsigned int refLength = 32; /* characters */
 
 
-static void search(const unsigned char * s, unsigned int len,
+static void search(const unsigned char * s, size_t len,
     StringSet & hashes, StringSet & seen)
 {
     static bool initialised = false;
@@ -25,7 +25,7 @@ static void search(const unsigned char * s, unsigned int len,
         initialised = true;
     }
 
-    for (unsigned int i = 0; i + refLength <= len; ) {
+    for (size_t i = 0; i + refLength <= len; ) {
         int j;
         bool match = true;
         for (j = refLength - 1; j >= 0; --j)
@@ -73,7 +73,7 @@ void RefScanSink::operator () (const unsigned char * data, size_t len)
 
     search(data, len, hashes, seen);
 
-    unsigned int tailLen = len <= refLength ? len : refLength;
+    size_t tailLen = len <= refLength ? len : refLength;
     tail =
         string(tail, tail.size() < refLength - tailLen ? 0 : tail.size() - (refLength - tailLen)) +
         string((const char *) data + len - tailLen, tailLen);
diff --git a/src/libutil/hash.cc b/src/libutil/hash.cc
index a01d651e1..9d82f13a5 100644
--- a/src/libutil/hash.cc
+++ b/src/libutil/hash.cc
@@ -82,7 +82,7 @@ static string printHash32(const Hash & hash)
     string s;
     s.reserve(len);
 
-    for (int n = len - 1; n >= 0; n--) {
+    for (int n = (int) len - 1; n >= 0; n--) {
         unsigned int b = n * 5;
         unsigned int i = b / 8;
         unsigned int j = b % 8;
diff --git a/src/libutil/serialise.hh b/src/libutil/serialise.hh
index d0b4552e3..6e703c52a 100644
--- a/src/libutil/serialise.hh
+++ b/src/libutil/serialise.hh
@@ -227,7 +227,7 @@ inline Sink & operator << (Sink & sink, uint64_t n)
     buf[4] = (n >> 32) & 0xff;
     buf[5] = (n >> 40) & 0xff;
     buf[6] = (n >> 48) & 0xff;
-    buf[7] = (n >> 56) & 0xff;
+    buf[7] = (unsigned char) (n >> 56) & 0xff;
     sink(buf, sizeof(buf));
     return sink;
 }
@@ -259,7 +259,7 @@ T readNum(Source & source)
     if (n > std::numeric_limits<T>::max())
         throw SerialisationError("serialised integer %d is too large for type '%s'", n, typeid(T).name());
 
-    return n;
+    return (T) n;
 }
 
 
diff --git a/src/libutil/xml-writer.cc b/src/libutil/xml-writer.cc
index 98bd058d1..e5cc2e9fc 100644
--- a/src/libutil/xml-writer.cc
+++ b/src/libutil/xml-writer.cc
@@ -28,7 +28,7 @@ void XMLWriter::close()
 }
 
 
-void XMLWriter::indent_(unsigned int depth)
+void XMLWriter::indent_(size_t depth)
 {
     if (!indent) return;
     output << string(depth * 2, ' ');
@@ -75,7 +75,7 @@ void XMLWriter::writeAttrs(const XMLAttrs & attrs)
 {
     for (auto & i : attrs) {
         output << " " << i.first << "=\"";
-        for (unsigned int j = 0; j < i.second.size(); ++j) {
+        for (size_t j = 0; j < i.second.size(); ++j) {
             char c = i.second[j];
             if (c == '"') output << "&quot;";
             else if (c == '<') output << "&lt;";
diff --git a/src/libutil/xml-writer.hh b/src/libutil/xml-writer.hh
index 3cefe3712..b98b44526 100644
--- a/src/libutil/xml-writer.hh
+++ b/src/libutil/xml-writer.hh
@@ -44,7 +44,7 @@ public:
 private:
     void writeAttrs(const XMLAttrs & attrs);
 
-    void indent_(unsigned int depth);
+    void indent_(size_t depth);
 };
 
 
diff --git a/src/nix-env/nix-env.cc b/src/nix-env/nix-env.cc
index 97e66cbd9..f60ff9e07 100644
--- a/src/nix-env/nix-env.cc
+++ b/src/nix-env/nix-env.cc
@@ -198,13 +198,13 @@ static Path getDefNixExprPath()
 }
 
 
-static int getPriority(EvalState & state, DrvInfo & drv)
+static long getPriority(EvalState & state, DrvInfo & drv)
 {
     return drv.queryMetaInt("priority", 0);
 }
 
 
-static int comparePriorities(EvalState & state, DrvInfo & drv1, DrvInfo & drv2)
+static long comparePriorities(EvalState & state, DrvInfo & drv1, DrvInfo & drv2)
 {
     return getPriority(state, drv2) - getPriority(state, drv1);
 }
@@ -270,7 +270,7 @@ static DrvInfos filterBySelector(EvalState & state, const DrvInfos & allElems,
 
             for (auto & j : matches) {
                 DrvName drvName(j.first.queryName());
-                int d = 1;
+                long d = 1;
 
                 Newest::iterator k = newest.find(drvName.name);
 
@@ -578,7 +578,7 @@ static void upgradeDerivations(Globals & globals,
                             (upgradeType == utEq && d == 0) ||
                             upgradeType == utAlways)
                         {
-                            int d2 = -1;
+                            long d2 = -1;
                             if (bestElem != availElems.end()) {
                                 d2 = comparePriorities(*globals.state, *bestElem, *j);
                                 if (d2 == 0) d2 = compareVersions(bestVersion, newName.version);
@@ -784,22 +784,22 @@ typedef list<Strings> Table;
 
 void printTable(Table & table)
 {
-    unsigned int nrColumns = table.size() > 0 ? table.front().size() : 0;
+    auto nrColumns = table.size() > 0 ? table.front().size() : 0;
 
-    vector<unsigned int> widths;
+    vector<size_t> widths;
     widths.resize(nrColumns);
 
     for (auto & i : table) {
         assert(i.size() == nrColumns);
         Strings::iterator j;
-        unsigned int column;
+        size_t column;
         for (j = i.begin(), column = 0; j != i.end(); ++j, ++column)
             if (j->size() > widths[column]) widths[column] = j->size();
     }
 
     for (auto & i : table) {
         Strings::iterator j;
-        unsigned int column;
+        size_t column;
         for (j = i.begin(), column = 0; j != i.end(); ++j, ++column) {
             string s = *j;
             replace(s.begin(), s.end(), '\n', ' ');
diff --git a/src/nix-store/dotgraph.cc b/src/nix-store/dotgraph.cc
index 51dedcf0a..abdfa5e58 100644
--- a/src/nix-store/dotgraph.cc
+++ b/src/nix-store/dotgraph.cc
@@ -47,8 +47,7 @@ static string makeNode(const string & id, const string & label,
 static string symbolicName(const string & path)
 {
     string p = baseNameOf(path);
-    int dash = p.find('-');
-    return string(p, dash + 1);
+    return string(p, p.find('-') + 1);
 }