diff --git a/src/storage/SparseMatrix.h b/src/storage/SparseMatrix.h
index 943656e95..94d663d3b 100644
--- a/src/storage/SparseMatrix.h
+++ b/src/storage/SparseMatrix.h
@@ -208,7 +208,7 @@ public:
 			throw storm::exceptions::InvalidArgumentException("Trying to initialize from an Eigen matrix that has more columns than the target matrix.");
 		}
 
-		const _Index entryCount = eigenSparseMatrix.nonZeros();
+		const uint_fast64_t entryCount = eigenSparseMatrix.nonZeros();
 		nonZeroEntryCount = entryCount;
 		lastRow = 0;
 
@@ -279,7 +279,7 @@ public:
 				// Now copy the elements. As the matrix is in ColMajor format,
 				// we need to iterate over the columns to find the next non-zero
 				// entry.
-				int i = 0;
+				uint_fast64_t i = 0;
 				int currentRow = 0;
 				int currentColumn = 0;
 				while (i < entryCount) {
diff --git a/test/parser/ParseMdpTest.cpp b/test/parser/ParseMdpTest.cpp
index cfa50f1c7..53100426b 100644
--- a/test/parser/ParseMdpTest.cpp
+++ b/test/parser/ParseMdpTest.cpp
@@ -20,10 +20,10 @@ TEST(ParseMdpTest, parseAndOutput) {
 	std::shared_ptr<storm::models::Mdp<double>> mdp = mdpParser->getMdp();
 	std::shared_ptr<storm::storage::SparseMatrix<double>> matrix = mdp->getTransitionProbabilityMatrix();
 
-	ASSERT_EQ(mdp->getNumberOfStates(), 3);
-	ASSERT_EQ(mdp->getNumberOfTransitions(), 11);
-	ASSERT_EQ(matrix->getRowCount(), 2 * 3);
-	ASSERT_EQ(matrix->getColumnCount(), 3);
+	ASSERT_EQ(mdp->getNumberOfStates(), (uint_fast64_t)3);
+	ASSERT_EQ(mdp->getNumberOfTransitions(), (uint_fast64_t)11);
+	ASSERT_EQ(matrix->getRowCount(), (uint_fast64_t)2 * 3);
+	ASSERT_EQ(matrix->getColumnCount(), (uint_fast64_t)3);
 	
 
 	delete mdpParser;