diff --git a/benchexec/tools/proton.py b/benchexec/tools/proton.py
index b21af9901..27955fb09 100644
--- a/benchexec/tools/proton.py
+++ b/benchexec/tools/proton.py
@@ -43,20 +43,22 @@ def determine_result(self, run):
 
             if result_str == "TRUE":
                 status = result.RESULT_TRUE_PROP
-            elif "FALSE" in result_str:
-                if result_str == "FALSE(termination)":
-                    status = result.RESULT_FALSE_TERMINATION
-                else:
-                    status = result.RESULT_FALSE_REACH
+
+            elif "FALSE(termination)" in result_str:
+                status = result.RESULT_FALSE_TERMINATION
+
             elif "UNKNOWN" in output:
                 status = result.RESULT_UNKNOWN
 
+            elif "INTERNAL-ERROR" in result_str:
+                status = "OUT-OF-MEMORY or INTERNAL-ERROR"
+
+            elif "INCONCLUSIVE" in result_str:
+                status = "INCONCLUSIVE"
+
         elif run.exit_code.value == 64 and "Usage error!" in output:
             status = "INVALID ARGUMENTS"
 
-        elif run.exit_code.value == 6:
-            status = "OUT-OF-MEMORY or INTERNAL-ERROR"
-
         else:
             status = result.RESULT_ERROR