diff --git a/library/Process-linux.cpp b/library/Process-linux.cpp
index 4a66470f9..1fecbab78 100644
--- a/library/Process-linux.cpp
+++ b/library/Process-linux.cpp
@@ -127,6 +127,9 @@ void Process::getMemRanges( vector<t_memrange> & ranges )
     char permissions[5]; // r/-, w/-, x/-, p/s, 0
 
     FILE *mapFile = ::fopen("/proc/self/maps", "r");
+    if (!mapFile)
+        return;
+
     size_t start, end, offset, device1, device2, node;
 
     while (fgets(buffer, 1024, mapFile))
@@ -148,6 +151,8 @@ void Process::getMemRanges( vector<t_memrange> & ranges )
         temp.valid = true;
         ranges.push_back(temp);
     }
+
+    fclose(mapFile);
 }
 
 uint32_t Process::getBase()
diff --git a/plugins/tweak.cpp b/plugins/tweak.cpp
index de7695fb3..bebc346c5 100644
--- a/plugins/tweak.cpp
+++ b/plugins/tweak.cpp
@@ -89,10 +89,10 @@ DFhackCExport command_result plugin_init (color_ostream &out, std::vector <Plugi
         "    Fixes rendering of creature weight limits in pressure plate build menu.\n"
         "  tweak stable-temp [disable]\n"
         "    Fixes performance bug 6012 by squashing jitter in temperature updates.\n"
-        "  tweak fast-heat [max-ticks]\n"
+        "  tweak fast-heat <max-ticks>\n"
         "    Further improves temperature updates by ensuring that 1 degree of\n"
         "    item temperature is crossed in no more than specified number of frames\n"
-        "    when updating from the environment temperature.\n"
+        "    when updating from the environment temperature. Use 0 to disable.\n"
     ));
     return CR_OK;
 }