diff --git a/src/lib/varint.hpp b/src/lib/varint.hpp
index a70abe4..4e4382e 100644
--- a/src/lib/varint.hpp
+++ b/src/lib/varint.hpp
@@ -34,7 +34,7 @@ namespace VarInt {
         uint64_t currentPosition = initialPosition;
         uint8_t bits = 0;
         while (data[currentPosition] & 0b10000000 && currentPosition < initialPosition+4) {
-            returnValue = returnValue + ((0b01111111 & data[currentPosition]) << bits);
+            returnValue = returnValue + (((int32_t) 0b01111111 & data[currentPosition]) << bits);
 
             (*processedBytes)++;
             bits += 7;
@@ -48,7 +48,7 @@ namespace VarInt {
         if (data[currentPosition] & 0b10000000) {
             return ErrorOr<int32_t>(true, ErrorCodes::OVERFLOW);
         }
-        returnValue = returnValue + ((0b01111111 & data[currentPosition]) << bits);
+        returnValue = returnValue + (((int32_t) 0b01111111 & data[currentPosition]) << bits);
         (*processedBytes)++;
 
         return ErrorOr<int32_t>(returnValue);
@@ -65,7 +65,7 @@ namespace VarInt {
         uint64_t currentPosition = initialPosition;
         uint8_t bits = 0;
         while (data[currentPosition] & 0b10000000 && currentPosition < initialPosition+9) {
-            returnValue = returnValue + ((0b01111111 & data[currentPosition]) << bits);
+            returnValue = returnValue + (((int64_t) 0b01111111 & data[currentPosition]) << bits);
 
             (*processedBytes)++;
             bits += 7;
@@ -78,7 +78,7 @@ namespace VarInt {
         if (data[currentPosition] & 0b10000000) {
             return ErrorOr<int64_t>(true, ErrorCodes::OVERFLOW);
         }
-        returnValue = returnValue + ((0b00000001 & data[currentPosition]) << bits);
+        returnValue = returnValue + (((int64_t) 0b01111111 & data[currentPosition]) << bits);
         (*processedBytes)++;
 
         return ErrorOr<int64_t>(returnValue);
diff --git a/src/test/varint.cpp b/src/test/varint.cpp
index 8a32424..90e70a7 100644
--- a/src/test/varint.cpp
+++ b/src/test/varint.cpp
@@ -39,7 +39,7 @@ int main() {
     //
     // 64 Bit
     // 0010 0000 0001 0000 0000 0000 1010 0010 1010 1000 0010 0000 1101 0000 1001 0011 = 2310347307446489235 -> 1101 0011 1010 0001 1000 0011 1100 0001 1010 1010 1001 0100 1000 0000 1000 1000 0010 0000
-    // 1000 0000 0100 0000 0010 0000 0001 0000 0000 1000 0000 0100 0000 0010 0000 0001 = 9241421688590303745 -> 1000 0001 1000 0100 1001 0000 1100 0000 1000 0000 1000 0010 1000 1000 1010 0000 1000 0000 0000 0001
+    // 1000 0000 0100 0000 0010 0000 0001 0000 0000 1000 0000 0100 0000 0010 0000 0001 = -9205322385119247871 -> 1000 0001 1000 0100 1001 0000 1100 0000 1000 0000 1000 0010 1000 1000 1010 0000 1000 0000 0000 0001
     // 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 = -1 (unsigned int64 max) -> 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 0000 0001
 
     uint8_t zeroProcessedBytes = 0;
@@ -112,9 +112,7 @@ int main() {
     minusOne64Data.push_back(1);
     ErrorOr<int64_t> minusOne64 = VarInt::fromVar64(minusOne64Data, 0, &minusOne64ProcessedBytes);
     ASSERT(!minusOne64.isError);
-    //FIXME: We get -9 here, WTF?
-    //std::cout << minusOne64.value << std::endl;
-    //ASSERT(minusOne64.value == -1);
+    ASSERT(minusOne64.value == -1);
     ASSERT(minusOne64ProcessedBytes == 10);
 
     // 0010 0000 0001 0000 0000 0000 1010 0010 1010 1000 0010 0000 1101 0000 1001 0011 = 2310347307446489235 -> 1101 0011 1010 0001 1000 0011 1100 0001 1010 1010 1001 0100 1000 0000 1000 1000 0010 0000
@@ -124,7 +122,7 @@ int main() {
     small64Data.push_back(0b11010011);
     small64Data.push_back(0b11010011);
     small64Data.push_back(0b11010011);
-    small64Data.push_back(0b11010011);
+    small64Data.push_back(0b10010011);
     small64Data.push_back(0b10100001);
     small64Data.push_back(0b10000011);
     small64Data.push_back(0b11000001);
@@ -133,23 +131,32 @@ int main() {
     small64Data.push_back(0b10000000);
     small64Data.push_back(0b10001000);
     small64Data.push_back(0b00100000);
-    //ErrorOr<int64_t> small64 = VarInt::fromVar64(small64Data, 3, &small64ProcessedBytes);
-    //ASSERT(!small64.isError);
-    //std::cout << small64.value << std::endl;
-    //ASSERT(small64.value == 2310347307446489235);
-    //ASSERT(small64ProcessedBytes == 9);
+    ErrorOr<int64_t> small64 = VarInt::fromVar64(small64Data, 3, &small64ProcessedBytes);
+    ASSERT(!small64.isError);
+    ASSERT(small64.value == 2310347307446489235);
+    ASSERT(small64ProcessedBytes == 9);
 
-    // 1000 0000 0100 0000 0010 0000 0001 0000 0000 1000 0000 0100 0000 0010 0000 0001 = 9241421688590303745 -> 1000 0001 1000 0100 1001 0000 1100 0000 1000 0000 1000 0010 1000 1000 1010 0000 1000 0000 0000 0001
+    // 1000 0000 0100 0000 0010 0000 0001 0000 0000 1000 0000 0100 0000 0010 0000 0001 = -9205322385119247871 -> 1000 0001 1000 0100 1001 0000 1100 0000 1000 0000 1000 0010 1000 1000 1010 0000 1000 0000 0000 0001
     uint8_t big64ProcessedBytes = 0;
     std::vector<uint8_t> big64Data;
-    big64Data.push_back(0b10111101);
-    big64Data.push_back(0b11111011);
+    big64Data.push_back(0b10000001);
+    big64Data.push_back(0b10000100);
     big64Data.push_back(0b10010000);
+    big64Data.push_back(0b11000000);
+    big64Data.push_back(0b10000000);
+    big64Data.push_back(0b10000010);
+    big64Data.push_back(0b10001000);
+    big64Data.push_back(0b10100000);
+    big64Data.push_back(0b10000000);
     big64Data.push_back(0b00000001);
-    //ErrorOr<int64_t> big64 = VarInt::fromVar64(big64Data, 0, &big64ProcessedBytes);
-    //ASSERT(!big64.isError);
-    //ASSERT(big64.value == 2375101);
-    //ASSERT(big64ProcessedBytes == 4);
+    ErrorOr<int64_t> big64 = VarInt::fromVar64(big64Data, 0, &big64ProcessedBytes);
+    ASSERT(!big64.isError);
+    ASSERT(big64.value == -9205322385119247871);
+    ASSERT(big64ProcessedBytes == 10);
+
+    //TODO: Test error conditions
+
+    std::cout << "Passed fromVar64 test." << std::endl;
 
 
     return 0;