diff --git a/Content.Tests/DMProject/Tests/Text/findlasttext.dm b/Content.Tests/DMProject/Tests/Text/findlasttext.dm
new file mode 100644
index 0000000000..c8d6eb403b
--- /dev/null
+++ b/Content.Tests/DMProject/Tests/Text/findlasttext.dm
@@ -0,0 +1,20 @@
+/proc/RunTest()
+	ASSERT(findlasttext("abcdefg", "f", 0, -1) == 0)
+	ASSERT(findlasttext("abcdefg", "f", 0, -2) == 6)
+	ASSERT(findlasttext("abcdefg", "f", 6) == 6)
+	ASSERT(findlasttext("abcdefg", "f", 5) == 0)
+	ASSERT(findlasttext("abcdefg", "bc", 2) == 2)
+	ASSERT(findlasttext("abcdefg", "ab", 10) == 1)
+	ASSERT(findlasttext("abcdefg", "f", 5) == 0)
+	ASSERT(findlasttext("Banana", "na", -3) == 3)
+	ASSERT(findlasttext("Banana", "na", -5) == 0)
+	ASSERT(findlasttext("Banana", "na", 0) == 5)
+	ASSERT(findlasttext("Banana", "na", 3) == 3)
+	ASSERT(findlasttext("Banana", "na", 2) == 0)
+	ASSERT(findlasttext("Banana", "na", 5) == 5)
+	ASSERT(findlasttext("Banana", "na", 50) == 5)
+	ASSERT(findlasttext("Banana", "na", -50) == 0)
+	ASSERT(findlasttext("abcdefg", "f", 6, -50) == 6)
+	ASSERT(findlasttext("abcdefg", "f", 6, 50) == 0)
+
+	
\ No newline at end of file
diff --git a/OpenDreamRuntime/Procs/Native/DreamProcNativeRoot.cs b/OpenDreamRuntime/Procs/Native/DreamProcNativeRoot.cs
index b1d4a4caa6..c32d09ac95 100644
--- a/OpenDreamRuntime/Procs/Native/DreamProcNativeRoot.cs
+++ b/OpenDreamRuntime/Procs/Native/DreamProcNativeRoot.cs
@@ -685,8 +685,8 @@ public static DreamValue NativeProc_findtextEx(NativeProc.Bundle bundle, DreamOb
         [DreamProc("findlasttext")]
         [DreamProcParameter("Haystack", Type = DreamValueTypeFlag.String)]
         [DreamProcParameter("Needle", Type = DreamValueTypeFlag.String)]
-        [DreamProcParameter("Start", Type = DreamValueTypeFlag.Float, DefaultValue = 1)]
-        [DreamProcParameter("End", Type = DreamValueTypeFlag.Float, DefaultValue = 0)]
+        [DreamProcParameter("Start", Type = DreamValueTypeFlag.Float, DefaultValue = 0)]
+        [DreamProcParameter("End", Type = DreamValueTypeFlag.Float, DefaultValue = 1)]
         public static DreamValue NativeProc_findlasttext(NativeProc.Bundle bundle, DreamObject? src, DreamObject? usr) {
             // TODO This is for handling nulls, check if it works right for other bad types
             int failCount = 0;
@@ -700,26 +700,33 @@ public static DreamValue NativeProc_findlasttext(NativeProc.Bundle bundle, Dream
                 return new DreamValue(failCount == 2 ? 1 : 0);
             }
 
-            int start = bundle.GetArgument(2, "Start").MustGetValueAsInteger(); //1-indexed
-            int end = bundle.GetArgument(3, "End").MustGetValueAsInteger(); //1-indexed
+            int start = bundle.GetArgument(2, "Start").MustGetValueAsInteger(); //chars from the end
+            int end = bundle.GetArgument(3, "End").MustGetValueAsInteger(); //1-indexed from the beginning
+            int actualstart;
+            int actualcount;
 
-            if (end == 0) {
-                end = text.Length + 1;
-            }
+            if(start > 0)
+                actualstart = start-1;
+            else
+                actualstart = (text.Length-1) + start;
+            actualstart += needle.Length-1;
+            actualstart = Math.Max(Math.Min(text.Length, actualstart),0);
 
-            int needleIndex = text.LastIndexOf(needle, end - 1, end - start, StringComparison.OrdinalIgnoreCase);
-            if (needleIndex != -1) {
-                return new DreamValue(needleIndex + 1); //1-indexed
-            } else {
-                return new DreamValue(0);
-            }
+            if(end > 0)
+                actualcount = actualstart - (end-1);
+            else
+                actualcount  = actualstart - ((text.Length-1) + (end));
+            actualcount += needle.Length-1;
+            actualcount = Math.Max(Math.Min(actualstart+1, actualcount),0);
+            int needleIndex = text.LastIndexOf(needle, actualstart, actualcount, StringComparison.OrdinalIgnoreCase);
+            return new DreamValue(needleIndex + 1); //1-indexed, or 0 if not found (LastIndexOf returns -1 if not found)
         }
 
         [DreamProc("findlasttextEx")]
         [DreamProcParameter("Haystack", Type = DreamValueTypeFlag.String)]
         [DreamProcParameter("Needle", Type = DreamValueTypeFlag.String)]
-        [DreamProcParameter("Start", Type = DreamValueTypeFlag.Float, DefaultValue = 1)]
-        [DreamProcParameter("End", Type = DreamValueTypeFlag.Float, DefaultValue = 0)]
+        [DreamProcParameter("Start", Type = DreamValueTypeFlag.Float, DefaultValue = 0)]
+        [DreamProcParameter("End", Type = DreamValueTypeFlag.Float, DefaultValue = 1)]
         public static DreamValue NativeProc_findlasttextEx(NativeProc.Bundle bundle, DreamObject? src, DreamObject? usr) {
             // TODO This is for handling nulls, check if it works right for other bad types
             int failCount = 0;
@@ -735,17 +742,24 @@ public static DreamValue NativeProc_findlasttextEx(NativeProc.Bundle bundle, Dre
 
             int start = bundle.GetArgument(2, "Start").GetValueAsInteger(); //1-indexed
             int end = bundle.GetArgument(3, "End").GetValueAsInteger(); //1-indexed
-
-            if (end == 0) {
-                end = text.Length + 1;
-            }
-
-            int needleIndex = text.LastIndexOf(needle, end - 1, end - start, StringComparison.InvariantCulture);
-            if (needleIndex != -1) {
-                return new DreamValue(needleIndex + 1); //1-indexed
-            } else {
-                return new DreamValue(0);
-            }
+            int actualstart;
+            int actualcount;
+
+            if(start > 0)
+                actualstart = start-1;
+            else
+                actualstart = (text.Length-1) + start;
+            actualstart += needle.Length-1;
+            actualstart = Math.Max(Math.Min(text.Length, actualstart),0);
+
+            if(end > 0)
+                actualcount = actualstart - (end-1);
+            else
+                actualcount  = actualstart - ((text.Length-1) + (end));
+            actualcount += needle.Length-1;
+            actualcount = Math.Max(Math.Min(actualstart+1, actualcount),0);
+            int needleIndex = text.LastIndexOf(needle, actualstart, actualcount, StringComparison.InvariantCulture);
+            return new DreamValue(needleIndex + 1); //1-indexed, or 0 if not found (LastIndexOf returns -1 if not found)
         }
 
         [DreamProc("flick")]