diff --git a/src/Insect/Parser.purs b/src/Insect/Parser.purs
index ff28d3c..a2472bd 100644
--- a/src/Insect/Parser.purs
+++ b/src/Insect/Parser.purs
@@ -418,6 +418,7 @@ assignment = do
   var ← token.identifier
   reservedOp "="
   value ← expression
+  eof
   pure $ Tuple var value
 
 -- | Try to parse the identifier as a unit, and fail if it succeeds.
diff --git a/test/Main.purs b/test/Main.purs
index 89ca3f4..b8e97c0 100644
--- a/test/Main.purs
+++ b/test/Main.purs
@@ -575,6 +575,7 @@ main = runTest do
       shouldFail "x+2=3"
       shouldFail "3=5"
       shouldFail "x="
+      shouldFail "x=3+"
 
     test "Reserved names" do
       shouldFail "m=2" -- 'm' is reserved unit