diff --git a/mypyc/irbuild/format_str_tokenizer.py b/mypyc/irbuild/format_str_tokenizer.py
index 2596e8e050a6..2a4212b55a6d 100644
--- a/mypyc/irbuild/format_str_tokenizer.py
+++ b/mypyc/irbuild/format_str_tokenizer.py
@@ -53,9 +53,9 @@ def generate_format_ops(specifiers: list[ConversionSpecifier]) -> list[FormatOp]
     format_ops = []
     for spec in specifiers:
         # TODO: Match specifiers instead of using whole_seq
-        if spec.whole_seq == "%s" or spec.whole_seq == "{:{}}":
+        if spec.whole_seq == "%s" or spec.whole_seq in ("{:{}}", ":s"):
             format_op = FormatOp.STR
-        elif spec.whole_seq == "%d":
+        elif spec.whole_seq in ("%d", ":d"):
             format_op = FormatOp.INT
         elif spec.whole_seq == "%b":
             format_op = FormatOp.BYTES
diff --git a/mypyc/test-data/irbuild-constant-fold.test b/mypyc/test-data/irbuild-constant-fold.test
index 009a4e68f678..19382ebb08db 100644
--- a/mypyc/test-data/irbuild-constant-fold.test
+++ b/mypyc/test-data/irbuild-constant-fold.test
@@ -192,9 +192,16 @@ L0:
 from typing import Any, Final
 
 FMT: Final = "{} {}"
+FMT_D: Final = "{:d} {:s}"
+FMT_S: Final = "{:s} {:s}"
 
 def f() -> str:
     return FMT.format(400 + 20, "roll" + "up")
+def g() -> str:
+    return FMT_D.format(400 + 20, "roll" + "up")
+def h() -> str:
+    return FMT_S.format(400 + 20, "roll" + "up")
+
 [out]
 def f():
     r0, r1, r2, r3 :: str
@@ -204,6 +211,22 @@ L0:
     r2 = ' '
     r3 = CPyStr_Build(3, r0, r2, r1)
     return r3
+def g():
+    r0, r1, r2, r3 :: str
+L0:
+    r0 = '420'
+    r1 = 'rollup'
+    r2 = ' '
+    r3 = CPyStr_Build(3, r0, r2, r1)
+    return r3
+def h():
+    r0, r1, r2, r3 :: str
+L0:
+    r0 = CPyTagged_Str(840)
+    r1 = 'rollup'
+    r2 = ' '
+    r3 = CPyStr_Build(3, r0, r2, r1)
+    return r3
 
 [case testIntConstantFoldingFinal]
 from typing import Final