diff --git a/src/cmd/fetch.zig b/src/cmd/fetch.zig
index f8f96441349f669f547904e094ab16458b740e41..7bdc9e053eee171257608f85c42097b629d08e94 100644
--- a/src/cmd/fetch.zig
+++ b/src/cmd/fetch.zig
@@ -67,6 +67,8 @@ pub fn create_depszig(alloc: std.mem.Allocator, cachepath: string, dir: std.fs.D
         \\        exe.linkSystemLibrary(libname);
         \\        exe.linkLibC();
         \\    }
+        \\    // clear module memo cache so addAllTo can be called more than once in the same build.zig
+        \\    inline for (comptime std.meta.declarations(package_data)) |decl| @field(package_data, decl.name).module_memo = null;
         \\}
         \\
         \\var link_lib_c = false;
diff --git a/src/cmd/generate.zig b/src/cmd/generate.zig
index 29c8758c0cd0ce5234266171d6b1b160c70e404d..5cc18b342f745106f3c05bbc658119c0c8d61432 100644
--- a/src/cmd/generate.zig
+++ b/src/cmd/generate.zig
@@ -133,6 +133,8 @@ pub fn create_depszig(alloc: std.mem.Allocator, cachepath: string, dir: std.fs.D
         \\        const module = pkg.module(exe, fetch_step);
         \\        exe.root_module.addImport(pkg.name, module);
         \\    }
+        \\    // clear module memo cache so addAllTo can be called more than once in the same build.zig
+        \\    inline for (comptime std.meta.declarations(package_data)) |decl| @field(package_data, decl.name).module_memo = null;
         \\}
         \\
         \\var link_lib_c = false;