diff --git a/Cargo.lock b/Cargo.lock
index f16d577e3..b17e9b739 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -62,9 +62,9 @@ dependencies = [
 
 [[package]]
 name = "anyhow"
-version = "1.0.82"
+version = "1.0.83"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f538837af36e6f6a9be0faa67f9a314f8119e4e4b5867c6ab40ed60360142519"
+checksum = "25bdb32cbbdce2b519a9cd7df3a678443100e265d5e25ca763b7572a5104f5f3"
 
 [[package]]
 name = "ariadne"
@@ -127,9 +127,9 @@ checksum = "cf4b9d6a944f767f8e5e0db018570623c85f3d925ac718db4e06d0187adb21c1"
 
 [[package]]
 name = "cc"
-version = "1.0.96"
+version = "1.0.97"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "065a29261d53ba54260972629f9ca6bffa69bac13cd1fed61420f7fa68b9f8bd"
+checksum = "099a5357d84c4c61eb35fc8eafa9a79a902c2f76911e5747ced4e032edd8d9b4"
 dependencies = [
  "jobserver",
  "libc",
@@ -370,9 +370,9 @@ checksum = "a47c1c47d2f5964e29c61246e81db715514cd532db6b5116a25ea3c03d6780a2"
 
 [[package]]
 name = "ena"
-version = "0.14.2"
+version = "0.14.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c533630cf40e9caa44bd91aadc88a75d75a4c3a12b4cfde353cbed41daa1e1f1"
+checksum = "3d248bdd43ce613d87415282f69b9bb99d947d290b10962dd6c56233312c2ad5"
 dependencies = [
  "log",
 ]
@@ -442,9 +442,9 @@ dependencies = [
 
 [[package]]
 name = "getrandom"
-version = "0.2.14"
+version = "0.2.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "94b22e06ecb0110981051723910cbf0b5f5e09a2062dd7663334ee79a9d1286c"
+checksum = "c4567c8db10ae91089c99af84c68c38da3ec2f087c3f82960bcdbf3656b6f4d7"
 dependencies = [
  "cfg-if",
  "libc",
@@ -874,9 +874,9 @@ checksum = "925383efa346730478fb4838dbe9137d2a47675ad789c546d150a6e1dd4ab31c"
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.81"
+version = "1.0.82"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3d1597b0c024618f09a9c3b8655b7e430397a36d23fdafec26d6965e9eec3eba"
+checksum = "8ad3d49ab951a01fbaafe34f2ec74122942fe18a3f9814c3268f1bb72042131b"
 dependencies = [
  "unicode-ident",
 ]
@@ -975,9 +975,9 @@ dependencies = [
 
 [[package]]
 name = "rustversion"
-version = "1.0.15"
+version = "1.0.16"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "80af6f9131f277a45a3fba6ce8e2258037bb0477a67e610d3c1fe046ab31de47"
+checksum = "092474d1a01ea8278f69e6a358998405fae5b8b963ddaeb2b0b04a128bf1dfb0"
 
 [[package]]
 name = "same-file"
@@ -996,9 +996,9 @@ checksum = "94143f37725109f92c262ed2cf5e59bce7498c01bcc1502d7b9afe439a4e9f49"
 
 [[package]]
 name = "semver"
-version = "1.0.22"
+version = "1.0.23"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "92d43fe69e652f3df9bdc2b85b2854a0825b86e4fb76bc44d945137d053639ca"
+checksum = "61697e0a1c7e512e84a621326239844a24d8207b4669b41bc18b32ea5cbf988b"
 
 [[package]]
 name = "serde"
@@ -1071,9 +1071,9 @@ checksum = "7da8b5736845d9f2fcb837ea5d9e2628564b3b043a70948a3f0b778838c5fb4f"
 
 [[package]]
 name = "syn"
-version = "2.0.60"
+version = "2.0.61"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "909518bc7b1c9b779f1bbf07f2929d35af9f0f37e47c6e9ef7f9dddc1e1821f3"
+checksum = "c993ed8ccba56ae856363b1845da7266a7cb78e1d146c8a32d54b45a8b831fc9"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -1138,18 +1138,18 @@ dependencies = [
 
 [[package]]
 name = "thiserror"
-version = "1.0.59"
+version = "1.0.60"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f0126ad08bff79f29fc3ae6a55cc72352056dfff61e3ff8bb7129476d44b23aa"
+checksum = "579e9083ca58dd9dcf91a9923bb9054071b9ebbd800b342194c9feb0ee89fc18"
 dependencies = [
  "thiserror-impl",
 ]
 
 [[package]]
 name = "thiserror-impl"
-version = "1.0.59"
+version = "1.0.60"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d1cd413b5d558b4c5bf3680e324a6fa5014e7b7c067a51e69dbdf47eb7148b66"
+checksum = "e2470041c06ec3ac1ab38d0356a6119054dedaea53e12fbefc0de730a1c08524"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -1535,9 +1535,9 @@ checksum = "bec47e5bfd1bff0eeaf6d8b485cc1074891a197ab4225d504cb7a1ab88b02bf0"
 
 [[package]]
 name = "winnow"
-version = "0.6.7"
+version = "0.6.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "14b9415ee827af173ebb3f15f9083df5a122eb93572ec28741fb153356ea2578"
+checksum = "c3c52e9c97a68071b23e836c9380edae937f17b9c4667bd021973efc689f618d"
 dependencies = [
  "memchr",
 ]
diff --git a/lib/edlang_check/src/lib.rs b/lib/edlang_check/src/lib.rs
index 8e6b3223c..4a580b3db 100644
--- a/lib/edlang_check/src/lib.rs
+++ b/lib/edlang_check/src/lib.rs
@@ -182,5 +182,21 @@ pub fn lowering_error_to_report(
                 )
                 .finish()
         }
+        LoweringError::ParamCountMismatch {
+            span,
+            has_args,
+            needs,
+            file_id,
+        } => {
+            let path = session.file_paths[file_id].display().to_string();
+            Report::build(ReportKind::Error, path.clone(), span.lo)
+                .with_code("ParamCountMismatch")
+                .with_label(
+                    Label::new((path, span.into()))
+                        .with_message(format!("function call parameter count mismatch: has {}, needs {}.", has_args, needs))
+                        .with_color(colors.next()),
+                )
+                .finish()
+        },
     }
 }
diff --git a/lib/edlang_lowering/src/errors.rs b/lib/edlang_lowering/src/errors.rs
index d0498cf1c..321262788 100644
--- a/lib/edlang_lowering/src/errors.rs
+++ b/lib/edlang_lowering/src/errors.rs
@@ -63,4 +63,11 @@ pub enum LoweringError {
         name: String,
         file_id: usize,
     },
+    #[error("parameter count mismatch to function call")]
+    ParamCountMismatch {
+        span: Span,
+        has_args: usize,
+        needs: usize,
+        file_id: usize,
+    },
 }
diff --git a/lib/edlang_lowering/src/lib.rs b/lib/edlang_lowering/src/lib.rs
index c29daf99e..18ccc3af9 100644
--- a/lib/edlang_lowering/src/lib.rs
+++ b/lib/edlang_lowering/src/lib.rs
@@ -1000,12 +1000,29 @@ fn lower_fn_call(
         }
     };
 
+    if args_ty.len() != info.params.len() {
+        return Err(LoweringError::ParamCountMismatch {
+            span: info.span,
+            has_args: info.params.len(),
+            needs: args_ty.len(),
+            file_id: builder.file_id,
+        });
+    }
+
     let mut args = Vec::new();
 
-    assert_eq!(args_ty.len(), info.params.len(), "param length mismatch");
-
     for (arg, arg_ty) in info.params.iter().zip(args_ty) {
-        let (rvalue, _rvalue_ty, _span) = lower_expr(builder, arg, Some(&arg_ty))?;
+        let (rvalue, rvalue_ty, arg_span) = lower_expr(builder, arg, Some(&arg_ty))?;
+
+        if rvalue_ty != arg_ty.kind {
+            return Err(LoweringError::UnexpectedType {
+                span: arg_span,
+                found: rvalue_ty,
+                expected: arg_ty,
+                file_id: builder.file_id,
+            });
+        }
+
         args.push(rvalue);
     }
 
diff --git a/program b/program
deleted file mode 100755
index bac4636d7..000000000
Binary files a/program and /dev/null differ