diff --git a/src/ir.cpp b/src/ir.cpp
index ef3426d111f8e111b4878706dd8b631a7bed1cb3..0687d18ef2f12f7c47ed3b99e05836b949c14ad1 100644
--- a/src/ir.cpp
+++ b/src/ir.cpp
@@ -11864,7 +11864,7 @@ static ConstCastOnly types_match_const_cast_only(IrAnalyze *ira, ZigType *wanted
         }
         assert(wanted_type->data.fn.is_generic ||
                 wanted_type->data.fn.fn_type_id.next_param_index  == wanted_type->data.fn.fn_type_id.param_count);
-        for (size_t i = 0; i < wanted_type->data.fn.fn_type_id.next_param_index; i += 1) {
+        for (size_t i = 0; i < wanted_type->data.fn.fn_type_id.param_count; i += 1) {
             // note it's reversed for parameters
             FnTypeParamInfo *actual_param_info = &actual_type->data.fn.fn_type_id.param_info[i];
             FnTypeParamInfo *expected_param_info = &wanted_type->data.fn.fn_type_id.param_info[i];
@@ -30285,7 +30285,7 @@ static ZigType *ir_resolve_lazy_fn_type(IrAnalyze *ira, AstNode *source_node, La
         if (param_is_var_args) {
             if (fn_type_id.cc == CallingConventionC) {
                 fn_type_id.param_count = fn_type_id.next_param_index;
-                continue;
+                break;
             } else if (fn_type_id.cc == CallingConventionUnspecified) {
                 return get_generic_fn_type(ira->codegen, &fn_type_id);
             } else {
diff --git a/src/parser.cpp b/src/parser.cpp
index a4dc324b2fe26da94c7a75933d8207cb5a2a1a68..0da7aac6399bd688aa1d647773d236c72c158be0 100644
--- a/src/parser.cpp
+++ b/src/parser.cpp
@@ -806,7 +806,7 @@ static AstNode *ast_parse_fn_proto(ParseContext *pc) {
         if (param_decl->data.param_decl.is_var_args)
             res->data.fn_proto.is_var_args = true;
         if (i != params.length - 1 && res->data.fn_proto.is_var_args)
-            ast_error(pc, first, "Function prototype have varargs as a none last paramter.");
+            ast_error(pc, first, "Function prototype have varargs as a none last parameter.");
     }
     return res;
 }
diff --git a/test/compile_errors.zig b/test/compile_errors.zig
index 341062e161f5d26dfbc04c76e3e4bf43caef0c0d..0af07d3ecebfbfa778fb336e1ac03faa177ec5c9 100644
--- a/test/compile_errors.zig
+++ b/test/compile_errors.zig
@@ -3,6 +3,17 @@ const builtin = @import("builtin");
 const Target = @import("std").Target;
 
 pub fn addCases(cases: *tests.CompileErrorContext) void {
+    cases.addTest("type mismatch in C prototype with varargs",
+        \\const fn_ty = ?fn ([*c]u8, ...) callconv(.C) void;
+        \\extern fn fn_decl(fmt: [*:0]u8, ...) void;
+        \\
+        \\export fn main() void {
+        \\    const x: fn_ty = fn_decl;
+        \\}
+    , &[_][]const u8{
+        "tmp.zig:5:22: error: expected type 'fn([*c]u8, ...) callconv(.C) void', found 'fn([*:0]u8, ...) callconv(.C) void'",
+    });
+
     cases.addTest("dependency loop in top-level decl with @TypeInfo",
         \\export const foo = @typeInfo(@This());
     , &[_][]const u8{