diff --git a/tools/python/src/cca.cpp b/tools/python/src/cca.cpp
index eca521a68..bdb6dcfb0 100644
--- a/tools/python/src/cca.cpp
+++ b/tools/python/src/cca.cpp
@@ -48,7 +48,7 @@ matrix<double,0,1> apply_cca_transform (
     const sparse_vect& v
 )
 {
-    pyassert(max_index_plus_one(v) <= m.nr(), "Invalid Inputs");
+    pyassert((long)max_index_plus_one(v) <= m.nr(), "Invalid Inputs");
     return sparse_matrix_vector_multiply(trans(m), v);
 }
 
diff --git a/tools/python/src/svm_c_trainer.cpp b/tools/python/src/svm_c_trainer.cpp
index 1d35a5567..1229868a3 100644
--- a/tools/python/src/svm_c_trainer.cpp
+++ b/tools/python/src/svm_c_trainer.cpp
@@ -137,7 +137,7 @@ const binary_test _cross_validate_trainer (
     const trainer_type& trainer,
     const std::vector<typename trainer_type::sample_type>& x,
     const std::vector<double>& y,
-    const long folds
+    const unsigned long folds
 )
 {
     pyassert(is_binary_classification_problem(x,y), "Training data does not make a valid training set.");
diff --git a/tools/python/src/vector.cpp b/tools/python/src/vector.cpp
index 833b11a70..19263658d 100644
--- a/tools/python/src/vector.cpp
+++ b/tools/python/src/vector.cpp
@@ -33,7 +33,7 @@ string cv__repr__ (const cv& v)
 {
     std::ostringstream sout;
     sout << "dlib.vector([";
-    for (unsigned long i = 0; i < v.size(); ++i)
+    for (long i = 0; i < v.size(); ++i)
     {
         sout << v(i);
         if (i+1 < v.size())