diff --git a/src/analyze.cpp b/src/analyze.cpp
index f1f294fdd..25065e9f8 100644
--- a/src/analyze.cpp
+++ b/src/analyze.cpp
@@ -898,7 +898,7 @@ static TypeTableEntry *get_generic_fn_type(CodeGen *g, FnTypeId *fn_type_id) {
     return fn_type;
 }
 
-void init_fn_type_id(FnTypeId *fn_type_id, AstNode *proto_node) {
+void init_fn_type_id(FnTypeId *fn_type_id, AstNode *proto_node, size_t param_count_alloc) {
     assert(proto_node->type == NodeTypeFnProto);
     AstNodeFnProto *fn_proto = &proto_node->data.fn_proto;
 
@@ -906,7 +906,7 @@ void init_fn_type_id(FnTypeId *fn_type_id, AstNode *proto_node) {
     fn_type_id->is_naked = fn_proto->is_nakedcc;
     fn_type_id->is_cold = fn_proto->is_coldcc;
     fn_type_id->param_count = fn_proto->params.length;
-    fn_type_id->param_info = allocate_nonzero<FnTypeParamInfo>(fn_type_id->param_count);
+    fn_type_id->param_info = allocate_nonzero<FnTypeParamInfo>(param_count_alloc);
     fn_type_id->next_param_index = 0;
     fn_type_id->is_var_args = fn_proto->is_var_args;
 }
@@ -916,7 +916,7 @@ static TypeTableEntry *analyze_fn_type(CodeGen *g, AstNode *proto_node, Scope *c
     AstNodeFnProto *fn_proto = &proto_node->data.fn_proto;
 
     FnTypeId fn_type_id = {0};
-    init_fn_type_id(&fn_type_id, proto_node);
+    init_fn_type_id(&fn_type_id, proto_node, proto_node->data.fn_proto.params.length);
 
     for (; fn_type_id.next_param_index < fn_type_id.param_count; fn_type_id.next_param_index += 1) {
         AstNode *param_node = fn_proto->params.at(fn_type_id.next_param_index);
diff --git a/src/analyze.hpp b/src/analyze.hpp
index 2af001055..c22835f03 100644
--- a/src/analyze.hpp
+++ b/src/analyze.hpp
@@ -70,7 +70,7 @@ VariableTableEntry *add_variable(CodeGen *g, AstNode *source_node, Scope *parent
 TypeTableEntry *analyze_type_expr(CodeGen *g, Scope *scope, AstNode *node);
 FnTableEntry *create_fn(AstNode *proto_node);
 FnTableEntry *create_fn_raw(FnInline inline_value, bool internal_linkage);
-void init_fn_type_id(FnTypeId *fn_type_id, AstNode *proto_node);
+void init_fn_type_id(FnTypeId *fn_type_id, AstNode *proto_node, size_t param_count_alloc);
 AstNode *get_param_decl_node(FnTableEntry *fn_entry, size_t index);
 FnTableEntry *scope_get_fn_if_root(Scope *scope);
 bool type_requires_comptime(TypeTableEntry *type_entry);
diff --git a/src/ir.cpp b/src/ir.cpp
index 48782ba90..ed4382d41 100644
--- a/src/ir.cpp
+++ b/src/ir.cpp
@@ -7866,7 +7866,7 @@ static TypeTableEntry *ir_analyze_fn_call(IrAnalyze *ira, IrInstructionCall *cal
         impl_fn->fndef_scope = create_fndef_scope(impl_fn->fn_def_node, parent_scope, impl_fn);
         impl_fn->child_scope = &impl_fn->fndef_scope->base;
         FnTypeId inst_fn_type_id = {0};
-        init_fn_type_id(&inst_fn_type_id, fn_proto_node);
+        init_fn_type_id(&inst_fn_type_id, fn_proto_node, call_param_count);
         inst_fn_type_id.param_count = 0;
         inst_fn_type_id.is_var_args = false;
 
@@ -7875,7 +7875,7 @@ static TypeTableEntry *ir_analyze_fn_call(IrAnalyze *ira, IrInstructionCall *cal
         GenericFnTypeId *generic_id = allocate<GenericFnTypeId>(1);
         generic_id->fn_entry = fn_entry;
         generic_id->param_count = 0;
-        generic_id->params = allocate<ConstExprValue>(src_param_count);
+        generic_id->params = allocate<ConstExprValue>(call_param_count);
         size_t next_proto_i = 0;
 
         if (first_arg_ptr) {
@@ -11483,7 +11483,7 @@ static TypeTableEntry *ir_analyze_instruction_fn_proto(IrAnalyze *ira, IrInstruc
     assert(proto_node->type == NodeTypeFnProto);
 
     FnTypeId fn_type_id = {0};
-    init_fn_type_id(&fn_type_id, proto_node);
+    init_fn_type_id(&fn_type_id, proto_node, proto_node->data.fn_proto.params.length);
 
     bool depends_on_compile_var = false;