diff --git a/src/script.cpp b/src/script.cpp
index 65e9b7c9a2..0b103a80bc 100644
--- a/src/script.cpp
+++ b/src/script.cpp
@@ -940,7 +940,7 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, co
                     // ([sig ...] num_of_signatures [pubkey ...] num_of_pubkeys -- bool)
 
                     int i = 1;
-                    if (stack.size() < i)
+                    if ((int)stack.size() < i)
                         return false;
 
                     int nKeysCount = CastToBigNum(stacktop(-i)).getint();
@@ -951,7 +951,7 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, co
                         return false;
                     int ikey = ++i;
                     i += nKeysCount;
-                    if (stack.size() < i)
+                    if ((int)stack.size() < i)
                         return false;
 
                     int nSigsCount = CastToBigNum(stacktop(-i)).getint();
@@ -959,7 +959,7 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, co
                         return false;
                     int isig = ++i;
                     i += nSigsCount;
-                    if (stack.size() < i)
+                    if ((int)stack.size() < i)
                         return false;
 
                     // Subset of script starting at the most recent codeseparator