diff --git a/src/schala_lang/eval.rs b/src/schala_lang/eval.rs
index 485da58..68987ec 100644
--- a/src/schala_lang/eval.rs
+++ b/src/schala_lang/eval.rs
@@ -85,6 +85,7 @@ impl ReplState {
     let opstr: &str = &op.0;
     Ok(match (opstr, evaled_lhs, evaled_rhs) {
       ("+", UnsignedInt(l), UnsignedInt(r)) => UnsignedInt(l + r),
+      ("+", Str(s1), Str(s2)) => Str(format!("{}{}", s1, s2)),
       ("-", UnsignedInt(l), UnsignedInt(r)) => UnsignedInt(l - r),
       ("*", UnsignedInt(l), UnsignedInt(r)) => UnsignedInt(l * r),
       ("/", UnsignedInt(l), UnsignedInt(r)) => UnsignedInt(l / r),
diff --git a/src/schala_lang/type_check.rs b/src/schala_lang/type_check.rs
index 7aa42f6..14791f2 100644
--- a/src/schala_lang/type_check.rs
+++ b/src/schala_lang/type_check.rs
@@ -214,10 +214,23 @@ impl TypeContext {
     })
   }
 
-  fn infer_op(&mut self, _op: &Operation) -> TypeCheckResult {
+  fn infer_op(&mut self, op: &Operation) -> TypeCheckResult {
     use self::Type::*;
     use self::TypeConst::*;
 
+    let opstr: &str = &op.0;
+    if opstr == "+" {
+      return Ok(
+        TConst(FunctionT(
+            Box::new(TConst(StringT)),
+            Box::new(TConst(FunctionT(
+                  Box::new(TConst(StringT)),
+                  Box::new(TConst(StringT))
+                  )))
+            ))
+        )
+    }
+
     Ok(
       TConst(FunctionT(
         Box::new(TConst(Integer)),