diff --git a/inc/qcbor/qcbor_decode.h b/inc/qcbor/qcbor_decode.h
index 1357beb..282ffde 100644
--- a/inc/qcbor/qcbor_decode.h
+++ b/inc/qcbor/qcbor_decode.h
@@ -1877,7 +1877,7 @@
 
 static inline int QCBOR_Int64ToUInt64(int64_t src, uint64_t *dest)
 {
-   if(src > 0) {
+   if(src < 0) {
       return -1;
    } else {
       *dest = (uint64_t) src;
diff --git a/test/qcbor_decode_tests.c b/test/qcbor_decode_tests.c
index 18e283e..1fdc7d9 100644
--- a/test/qcbor_decode_tests.c
+++ b/test/qcbor_decode_tests.c
@@ -4599,3 +4599,196 @@
    
    return 0;
 }
+
+
+
+int32_t IntToTests()
+{
+   int nErrCode;
+   int32_t n32;
+   int16_t n16;
+   int8_t n8;
+   uint32_t u32;
+   uint16_t u16;
+   uint8_t u8;
+   uint64_t u64;
+
+   nErrCode = QCBOR_Int64ToInt32(1, &n32);
+   if(nErrCode == -1 || n32 != 1) {
+      return 1;
+   }
+
+   nErrCode = QCBOR_Int64ToInt32((int64_t)INT32_MAX, &n32);
+   if(nErrCode == -1 || n32 != INT32_MAX) {
+      return 2;
+   }
+
+   nErrCode = QCBOR_Int64ToInt32((int64_t)INT32_MIN, &n32);
+   if(nErrCode == -1 || n32 != INT32_MIN) {
+      return 3;
+   }
+
+   nErrCode = QCBOR_Int64ToInt32(((int64_t)INT32_MAX)+1, &n32);
+   if(nErrCode != -1) {
+      return 4;
+   }
+
+   nErrCode = QCBOR_Int64ToInt32(((int64_t)INT32_MIN)-1, &n32);
+   if(nErrCode != -1) {
+      return 5;
+   }
+
+
+   nErrCode = QCBOR_Int64ToInt16((int64_t)INT16_MAX, &n16);
+   if(nErrCode == -1 || n16 != INT16_MAX) {
+      return 6;
+   }
+
+   nErrCode = QCBOR_Int64ToInt16((int64_t)INT16_MIN, &n16);
+   if(nErrCode == -1 || n16 != INT16_MIN) {
+      return 7;
+   }
+
+   nErrCode = QCBOR_Int64ToInt16(1, &n16);
+   if(nErrCode == -1 || n16 != 1) {
+      return 8;
+   }
+
+   nErrCode = QCBOR_Int64ToInt16(((int64_t)INT16_MAX)+1, &n16);
+   if(nErrCode != -1) {
+      return 9;
+   }
+
+   nErrCode = QCBOR_Int64ToInt16(((int64_t)INT16_MIN)-1, &n16);
+   if(nErrCode != -1) {
+      return 10;
+   }
+
+
+   nErrCode = QCBOR_Int64ToInt8(1, &n8);
+   if(nErrCode == -1 || n8 != 1) {
+      return 11;
+   }
+
+   nErrCode = QCBOR_Int64ToInt8((int64_t)INT8_MAX, &n8);
+   if(nErrCode == -1 || n8 != INT8_MAX) {
+      return 12;
+   }
+
+   nErrCode = QCBOR_Int64ToInt8((int64_t)INT8_MIN, &n8);
+   if(nErrCode == -1 || n8 != INT8_MIN) {
+      return 13;
+   }
+
+   nErrCode = QCBOR_Int64ToInt8(((int64_t)INT8_MAX)+1, &n8);
+   if(nErrCode != -1) {
+      return 14;
+   }
+
+   nErrCode = QCBOR_Int64ToInt8(((int64_t)INT8_MIN)-1, &n8);
+   if(nErrCode != -1) {
+      return 15;
+   }
+
+
+   nErrCode = QCBOR_Int64ToUInt32(1, &u32);
+   if(nErrCode == -1 || u32 != 1) {
+      return 16;
+   }
+
+   nErrCode = QCBOR_Int64ToUInt32((int64_t)UINT32_MAX, &u32);
+   if(nErrCode == -1 || u32 != UINT32_MAX) {
+      return 17;
+   }
+
+   nErrCode = QCBOR_Int64ToUInt32((int64_t)0, &u32);
+   if(nErrCode == -1 || u32 != 0) {
+      return 18;
+   }
+
+   nErrCode = QCBOR_Int64ToUInt32(((int64_t)UINT32_MAX)+1, &u32);
+   if(nErrCode != -1) {
+      return 19;
+   }
+
+   nErrCode = QCBOR_Int64ToUInt32((int64_t)-1, &u32);
+   if(nErrCode != -1) {
+      return 20;
+   }
+
+
+   nErrCode = QCBOR_Int64UToInt16((int64_t)UINT16_MAX, &u16);
+   if(nErrCode == -1 || u16 != UINT16_MAX) {
+      return 21;
+   }
+
+   nErrCode = QCBOR_Int64UToInt16((int64_t)0, &u16);
+   if(nErrCode == -1 || u16 != 0) {
+      return 22;
+   }
+
+   nErrCode = QCBOR_Int64UToInt16(1, &u16);
+   if(nErrCode == -1 || u16 != 1) {
+      return 23;
+   }
+
+   nErrCode = QCBOR_Int64UToInt16(((int64_t)UINT16_MAX)+1, &u16);
+   if(nErrCode != -1) {
+      return 24;
+   }
+
+   nErrCode = QCBOR_Int64UToInt16((int64_t)-1, &u16);
+   if(nErrCode != -1) {
+      return 25;
+   }
+
+
+   nErrCode = QCBOR_Int64ToUInt8((int64_t)UINT8_MAX, &u8);
+   if(nErrCode == -1 || u8 != UINT8_MAX) {
+      return 26;
+   }
+
+   nErrCode = QCBOR_Int64ToUInt8((int64_t)0, &u8);
+   if(nErrCode == -1 || u8 != 0) {
+      return 27;
+   }
+
+   nErrCode = QCBOR_Int64ToUInt8(1, &u8);
+   if(nErrCode == -1 || u8 != 1) {
+      return 28;
+   }
+
+   nErrCode = QCBOR_Int64ToUInt8(((int64_t)UINT16_MAX)+1, &u8);
+   if(nErrCode != -1) {
+      return 29;
+   }
+
+   nErrCode = QCBOR_Int64ToUInt8((int64_t)-1, &u8);
+   if(nErrCode != -1) {
+      return 30;
+   }
+
+
+   nErrCode = QCBOR_Int64ToUInt64(1, &u64);
+   if(nErrCode == -1 || u64 != 1) {
+      return 31;
+   }
+
+   nErrCode = QCBOR_Int64ToUInt64(INT64_MAX, &u64);
+   if(nErrCode == -1 || u64 != INT64_MAX) {
+      return 32;
+   }
+
+   nErrCode = QCBOR_Int64ToUInt64((int64_t)0, &u64);
+   if(nErrCode == -1 || u64 != 0) {
+      return 33;
+   }
+
+   nErrCode = QCBOR_Int64ToUInt64((int64_t)-1, &u64);
+   if(nErrCode != -1) {
+      return 34;
+   }
+
+   return 0;
+}
+
diff --git a/test/qcbor_decode_tests.h b/test/qcbor_decode_tests.h
index daabeab..5bb0d48 100644
--- a/test/qcbor_decode_tests.h
+++ b/test/qcbor_decode_tests.h
@@ -261,4 +261,9 @@
 int32_t CBORSequenceDecodeTests(void);
 
 
+/*
+Tests for functions to safely convert integer types.
+*/
+int32_t IntToTests(void);
+
 #endif /* defined(__QCBOR__qcbort_decode_tests__) */
diff --git a/test/run_tests.c b/test/run_tests.c
index bcf3fd1..a719654 100644
--- a/test/run_tests.c
+++ b/test/run_tests.c
@@ -107,6 +107,7 @@
     TEST_ENTRY(SimpleValuesIndefiniteLengthTest1),
     TEST_ENTRY(EncodeLengthThirtyoneTest),
     TEST_ENTRY(CBORSequenceDecodeTests),
+    TEST_ENTRY(IntToTests),
 #ifndef     QCBOR_CONFIG_DISABLE_EXP_AND_MANTISSA
     TEST_ENTRY(EncodeLengthThirtyoneTest),
     TEST_ENTRY(ExponentAndMantissaDecodeTests),