diff --git a/src/machine-c-api.h b/src/machine-c-api.h
index 5b3b93846..24da6b686 100644
--- a/src/machine-c-api.h
+++ b/src/machine-c-api.h
@@ -61,30 +61,30 @@ typedef enum cm_pma_constant {
 
 /// \brief Error codes returned from the C API.
 typedef enum cm_error {
-    CM_ERROR_OK,
-    CM_ERROR_INVALID_ARGUMENT,
-    CM_ERROR_DOMAIN_ERROR,
-    CM_ERROR_LENGTH_ERROR,
-    CM_ERROR_OUT_OF_RANGE,
-    CM_ERROR_LOGIC_ERROR,
-    CM_ERROR_RUNTIME_ERROR,
-    CM_ERROR_RANGE_ERROR,
-    CM_ERROR_OVERFLOW_ERROR,
-    CM_ERROR_UNDERFLOW_ERROR,
-    CM_ERROR_REGEX_ERROR,
-    CM_ERROR_SYSTEM_ERROR,
-    CM_ERROR_BAD_TYPEID,
-    CM_ERROR_BAD_CAST,
-    CM_ERROR_BAD_ANY_CAST,
-    CM_ERROR_BAD_OPTIONAL_ACCESS,
-    CM_ERROR_BAD_WEAK_PTR,
-    CM_ERROR_BAD_FUNCTION_CALL,
-    CM_ERROR_BAD_ALLOC,
-    CM_ERROR_BAD_ARRAY_NEW_LENGTH,
-    CM_ERROR_BAD_EXCEPTION,
-    CM_ERROR_BAD_VARIANT_ACCESS,
-    CM_ERROR_EXCEPTION,
-    CM_ERROR_UNKNOWN,
+    CM_ERROR_OK = 0,
+    CM_ERROR_INVALID_ARGUMENT = -1,
+    CM_ERROR_DOMAIN_ERROR = -2,
+    CM_ERROR_LENGTH_ERROR = -3,
+    CM_ERROR_OUT_OF_RANGE = -4,
+    CM_ERROR_LOGIC_ERROR = -5,
+    CM_ERROR_RUNTIME_ERROR = -6,
+    CM_ERROR_RANGE_ERROR = -7,
+    CM_ERROR_OVERFLOW_ERROR = -8,
+    CM_ERROR_UNDERFLOW_ERROR = -9,
+    CM_ERROR_REGEX_ERROR = -10,
+    CM_ERROR_SYSTEM_ERROR = -11,
+    CM_ERROR_BAD_TYPEID = -12,
+    CM_ERROR_BAD_CAST = -13,
+    CM_ERROR_BAD_ANY_CAST = -14,
+    CM_ERROR_BAD_OPTIONAL_ACCESS = -15,
+    CM_ERROR_BAD_WEAK_PTR = -16,
+    CM_ERROR_BAD_FUNCTION_CALL = -17,
+    CM_ERROR_BAD_ALLOC = -18,
+    CM_ERROR_BAD_ARRAY_NEW_LENGTH = -19,
+    CM_ERROR_BAD_EXCEPTION = -20,
+    CM_ERROR_BAD_VARIANT_ACCESS = -21,
+    CM_ERROR_EXCEPTION = -22,
+    CM_ERROR_UNKNOWN = -23,
 } cm_error;
 
 /// \brief Reasons for a machine run interruption.