diff --git a/crypto/func/func.h b/crypto/func/func.h
index 2ea1015e..c86f7e6b 100644
--- a/crypto/func/func.h
+++ b/crypto/func/func.h
@@ -1631,6 +1631,7 @@ inline compile_func_t make_ext_compile(AsmOp op) {
 struct SymValAsmFunc : SymValFunc {
   simple_compile_func_t simple_compile;
   compile_func_t ext_compile;
+  td::uint64 crc;
   ~SymValAsmFunc() override = default;
   SymValAsmFunc(TypeExpr* ft, const AsmOp& _macro, bool impure = false)
       : SymValFunc(-1, ft, impure), simple_compile(make_simple_compile(_macro)) {
diff --git a/crypto/func/parse-func.cpp b/crypto/func/parse-func.cpp
index 6118a433..92dfe47b 100644
--- a/crypto/func/parse-func.cpp
+++ b/crypto/func/parse-func.cpp
@@ -1270,19 +1270,48 @@ SymValAsmFunc* parse_asm_func_body(Lexer& lex, TypeExpr* func_type, const Formal
     lex.expect(')');
   }
   while (lex.tp() == _String) {
-    asm_ops.push_back(AsmOp::Parse(lex.cur().str, cnt, width));
-    lex.next();
-    if (asm_ops.back().is_custom()) {
-      cnt = width;
+    std::string ops = lex.cur().str; // <op>\n<op>\n...
+    std::string op;
+    for (const char& c : ops) {
+      if (c == '\n') {
+        if (!op.empty()) {
+          asm_ops.push_back(AsmOp::Parse(op, cnt, width));
+          if (asm_ops.back().is_custom()) {
+            cnt = width;
+          }
+          op.clear();
+        }
+      } else {
+        op.push_back(c);
+      }
     }
+    if (!op.empty()) {
+      asm_ops.push_back(AsmOp::Parse(op, cnt, width));
+      if (asm_ops.back().is_custom()) {
+        cnt = width;
+      }
+    }
+    lex.next();
   }
   if (asm_ops.empty()) {
     throw src::ParseError{lex.cur().loc, "string with assembler instruction expected"};
   }
   lex.expect(';');
+  std::string crc_s;
+  for (const AsmOp& asm_op : asm_ops) {
+    crc_s += asm_op.op;
+  }
+  crc_s.push_back(impure);
+  for (const int& x : arg_order) {
+    crc_s += std::string((const char*) (&x), (const char*) (&x + 1));
+  }
+  for (const int& x : ret_order) {
+    crc_s += std::string((const char*) (&x), (const char*) (&x + 1));
+  }
   auto res = new SymValAsmFunc{func_type, asm_ops, impure};
   res->arg_order = std::move(arg_order);
   res->ret_order = std::move(ret_order);
+  res->crc = td::crc64(crc_s);
   return res;
 }
 
@@ -1448,16 +1477,22 @@ void parse_func_def(Lexer& lex) {
     // code->print(std::cerr);  // !!!DEBUG!!!
     func_sym_code->code = code;
   } else {
+    Lexem asm_lexem = lex.cur();
+    SymValAsmFunc* asm_func = parse_asm_func_body(lex, func_type, arg_list, ret_type, impure);
     if (func_sym_val) {
       if (dynamic_cast<SymValCodeFunc*>(func_sym_val)) {
-        lex.cur().error("function `"s + func_name.str + "` was already declared as an ordinary function");
+        asm_lexem.error("function `"s + func_name.str + "` was already declared as an ordinary function");
       }
-      if (dynamic_cast<SymValAsmFunc*>(func_sym_val)) {
-        lex.cur().error("redefinition of built-in assembler function `"s + func_name.str + "`");
+      SymValAsmFunc* asm_func_old = dynamic_cast<SymValAsmFunc*>(func_sym_val);
+      if (asm_func_old) {
+        if (asm_func->crc != asm_func_old->crc) {
+          asm_lexem.error("redefinition of built-in assembler function `"s + func_name.str + "`");
+        }
+      } else {
+        asm_lexem.error("redefinition of previously (somehow) defined function `"s + func_name.str + "`");
       }
-      lex.cur().error("redefinition of previously (somehow) defined function `"s + func_name.str + "`");
     }
-    func_sym->value = parse_asm_func_body(lex, func_type, arg_list, ret_type, impure);
+    func_sym->value = asm_func;
   }
   if (method_id.not_null()) {
     auto val = dynamic_cast<SymVal*>(func_sym->value);
diff --git a/crypto/func/test/s2.fc b/crypto/func/test/s2.fc
new file mode 100644
index 00000000..c6df49d5
--- /dev/null
+++ b/crypto/func/test/s2.fc
@@ -0,0 +1,26 @@
+slice test1() asm """
+  "Test" $>s
+  PUSHSLICE
+""";
+
+slice test2() asm """
+  "Hello"
+  " "
+  "World"
+  $+ $+ $>s
+  PUSHSLICE
+""";
+
+int sdeq (slice s1, slice s2) asm """SDEQ""";
+int sdeq (slice s1, slice s2) asm "SDEQ" "";
+int sdeq (slice s1, slice s2) asm "" """
+SDEQ
+""";
+
+() main() {
+  slice s = test1();
+  throw_unless(101, sdeq(s, "Test"));
+
+  slice s = test2();
+  throw_unless(102, sdeq(s, "Hello World"));
+}
diff --git a/crypto/parser/lexer.cpp b/crypto/parser/lexer.cpp
index 5c5b77d8..624d8dd2 100644
--- a/crypto/parser/lexer.cpp
+++ b/crypto/parser/lexer.cpp
@@ -125,8 +125,9 @@ int Lexem::set(std::string _str, const SrcLocation& _loc, int _tp, int _val) {
 }
 
 Lexer::Lexer(SourceReader& _src, bool init, std::string active_chars, std::string eol_cmts, std::string open_cmts,
-             std::string close_cmts, std::string quote_chars)
-    : src(_src), eof(false), lexem("", src.here(), Lexem::Undefined), peek_lexem("", {}, Lexem::Undefined) {
+             std::string close_cmts, std::string quote_chars, std::string multiline_quote)
+    : src(_src), eof(false), lexem("", src.here(), Lexem::Undefined), peek_lexem("", {}, Lexem::Undefined),
+      multiline_quote(std::move(multiline_quote)) {
   std::memset(char_class, 0, sizeof(char_class));
   unsigned char activity = cc::active;
   for (char c : active_chars) {
@@ -171,6 +172,19 @@ void Lexer::set_spec(std::array<int, 3>& arr, std::string setup) {
   }
 }
 
+bool Lexer::is_multiline_quote(const char* begin, const char* end) {
+  if (multiline_quote.empty()) {
+    return false;
+  }
+  for (const char& c : multiline_quote) {
+    if (begin == end || *begin != c) {
+      return false;
+    }
+    ++begin;
+  }
+  return true;
+}
+
 void Lexer::expect(int exp_tp, const char* msg) {
   if (tp() != exp_tp) {
     throw ParseError{lexem.loc, (msg ? std::string{msg} : Lexem::lexem_name_str(exp_tp)) + " expected instead of " +
@@ -234,6 +248,37 @@ const Lexem& Lexer::next() {
     }
     return lexem.clear(src.here(), Lexem::Eof);
   }
+  if (is_multiline_quote(src.get_ptr(), src.get_end_ptr())) {
+    src.advance(multiline_quote.size());
+    const char* begin = src.get_ptr();
+    const char* end = nullptr;
+    SrcLocation here = src.here();
+    std::string body;
+    while (!src.is_eof()) {
+      if (src.is_eoln()) {
+        body.push_back('\n');
+        src.load_line();
+        continue;
+      }
+      if (is_multiline_quote(src.get_ptr(), src.get_end_ptr())) {
+        end = src.get_ptr();
+        src.advance(multiline_quote.size());
+        break;
+      }
+      body.push_back(src.cur_char());
+      src.advance(1);
+    }
+    if (!end) {
+      src.error("string extends past end of file");
+    }
+    lexem.set(body, here, Lexem::String);
+    int c = src.cur_char();
+    if ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z')) {
+      lexem.val = c;
+      src.advance(1);
+    }
+    return lexem;
+  }
   int c = src.cur_char();
   const char* end = src.get_ptr();
   if (is_quote_char(c) || c == '`') {
diff --git a/crypto/parser/lexer.h b/crypto/parser/lexer.h
index 12556e46..686d8eac 100644
--- a/crypto/parser/lexer.h
+++ b/crypto/parser/lexer.h
@@ -71,6 +71,7 @@ class Lexer {
   Lexem lexem, peek_lexem;
   unsigned char char_class[128];
   std::array<int, 3> eol_cmt, cmt_op, cmt_cl;
+  std::string multiline_quote;
   enum cc { left_active = 2, right_active = 1, active = 3, allow_repeat = 4, quote_char = 8 };
 
  public:
@@ -78,7 +79,8 @@ class Lexer {
     return eof;
   }
   Lexer(SourceReader& _src, bool init = false, std::string active_chars = ";,() ~.", std::string eol_cmts = ";;",
-        std::string open_cmts = "{-", std::string close_cmts = "-}", std::string quote_chars = "\"");
+        std::string open_cmts = "{-", std::string close_cmts = "-}", std::string quote_chars = "\"",
+        std::string multiline_quote = "\"\"\"");
   const Lexem& next();
   const Lexem& cur() const {
     return lexem;
@@ -109,6 +111,7 @@ class Lexer {
 
  private:
   void set_spec(std::array<int, 3>& arr, std::string setup);
+  bool is_multiline_quote(const char* begin, const char* end);
 };
 
 }  // namespace src
diff --git a/crypto/tl/tlbc.cpp b/crypto/tl/tlbc.cpp
index 127eacb0..01b8a31a 100644
--- a/crypto/tl/tlbc.cpp
+++ b/crypto/tl/tlbc.cpp
@@ -2423,7 +2423,7 @@ std::vector<const src::FileDescr*> source_fdescr;
 
 bool parse_source(std::istream* is, src::FileDescr* fdescr) {
   src::SourceReader reader{is, fdescr};
-  src::Lexer lex{reader, true, "(){}:;? #$. ^~ #", "//", "/*", "*/"};
+  src::Lexer lex{reader, true, "(){}:;? #$. ^~ #", "//", "/*", "*/", ""};
   while (lex.tp() != src::_Eof) {
     parse_constructor_def(lex);
     // std::cerr << lex.cur().str << '\t' << lex.cur().name_str() << std::endl;