diff --git a/compiler/src/dotty/tools/dotc/typer/Checking.scala b/compiler/src/dotty/tools/dotc/typer/Checking.scala
index 2869f64f33d0..305acea188da 100644
--- a/compiler/src/dotty/tools/dotc/typer/Checking.scala
+++ b/compiler/src/dotty/tools/dotc/typer/Checking.scala
@@ -584,6 +584,8 @@ object Checking {
       report.error(ModifierNotAllowedForDefinition(Sealed), flagSourcePos(Sealed))
     if mods.is(Final, butNot = Synthetic) then
       report.warning(RedundantModifier(Final), flagSourcePos(Final))
+    if mods.is(Infix) then
+      report.error(ModifierNotAllowedForDefinition(Infix), flagSourcePos(Infix))
 
   /** Check the type signature of the symbol `M` defined by `tree` does not refer
    *  to a private type or value which is invisible at a point where `M` is still
diff --git a/tests/neg/i17738-infix-object/NestedInfixObject.scala b/tests/neg/i17738-infix-object/NestedInfixObject.scala
new file mode 100644
index 000000000000..703cbef9e2ba
--- /dev/null
+++ b/tests/neg/i17738-infix-object/NestedInfixObject.scala
@@ -0,0 +1,2 @@
+object ToplevelObject:
+  infix object NestedInfixObject // error
diff --git a/tests/neg/i17738-infix-object/ToplevelInfixObject.scala b/tests/neg/i17738-infix-object/ToplevelInfixObject.scala
new file mode 100644
index 000000000000..1ee13265b06c
--- /dev/null
+++ b/tests/neg/i17738-infix-object/ToplevelInfixObject.scala
@@ -0,0 +1 @@
+infix object ToplevelInfixObject // error