diff --git a/bindings/pyroot/cppyy/CPyCppyy/src/Converters.cxx b/bindings/pyroot/cppyy/CPyCppyy/src/Converters.cxx
index 4ac294745cac9..830e504ba1266 100644
--- a/bindings/pyroot/cppyy/CPyCppyy/src/Converters.cxx
+++ b/bindings/pyroot/cppyy/CPyCppyy/src/Converters.cxx
@@ -2834,6 +2834,14 @@ bool CPyCppyy::SmartPtrConverter::SetArg(
         return true;
     }
 
+// The automatic conversion of ordinary obejcts to smart pointers is disabled
+// for PyROOT because it can cause trouble with overload resolution. If a
+// function has overloads for both ordinary objects and smart pointers, then
+// the implicit conversion to smart pointers can result in the smart pointer
+// overload being hit, even though there would be an overload for the regular
+// object. Since PyROOT didn't have this feature before 6.32 anyway, disabling
+// it was the safest option.
+#if 0
 // for the case where we have an ordinary object to convert
     if (!pyobj->IsSmart() && Cppyy::IsSubtype(oisa, fUnderlyingType)) {
     // create the relevant smart pointer and make the pyobject "smart"
@@ -2852,6 +2860,7 @@ bool CPyCppyy::SmartPtrConverter::SetArg(
 
         return true;
     }
+#endif
 
 // final option, try mapping pointer types held (TODO: do not allow for non-const ref)
     if (pyobj->IsSmart() && Cppyy::IsSubtype(oisa, fUnderlyingType)) {
diff --git a/bindings/pyroot/cppyy/patches/CPyCppyy-Disable-implicit-conversion-to-smart-ptr.patch b/bindings/pyroot/cppyy/patches/CPyCppyy-Disable-implicit-conversion-to-smart-ptr.patch
new file mode 100644
index 0000000000000..c6b431ae23a5f
--- /dev/null
+++ b/bindings/pyroot/cppyy/patches/CPyCppyy-Disable-implicit-conversion-to-smart-ptr.patch
@@ -0,0 +1,49 @@
+From 72df898c30db57c43d4cd3136435f36876596c6a Mon Sep 17 00:00:00 2001
+From: Jonas Rembser <jonas.rembser@cern.ch>
+Date: Thu, 4 Apr 2024 02:07:22 +0200
+Subject: [PATCH] [CPyCppyy] Disable automatic conversion of regular to smart
+ pointers
+
+The automatic conversion of ordinary obejcts to smart pointers is
+disabled for PyROOT because it can cause trouble with overload
+resolution. If a function has overloads for both ordinary objects and
+smart pointers, then the implicit conversion to smart pointers can
+result in the smart pointer overload being hit, even though there would
+be an overload for the regular object. Since PyROOT didn't have this
+feature before 6.32 anyway, disabling it was the safest option.
+
+Closes #15117.
+---
+ bindings/pyroot/cppyy/CPyCppyy/src/Converters.cxx | 9 +++++++++
+ 1 file changed, 9 insertions(+)
+
+diff --git a/bindings/pyroot/cppyy/CPyCppyy/src/Converters.cxx b/bindings/pyroot/cppyy/CPyCppyy/src/Converters.cxx
+index 4ac294745ca..830e504ba12 100644
+--- a/bindings/pyroot/cppyy/CPyCppyy/src/Converters.cxx
++++ b/bindings/pyroot/cppyy/CPyCppyy/src/Converters.cxx
+@@ -2834,6 +2834,14 @@ bool CPyCppyy::SmartPtrConverter::SetArg(
+         return true;
+     }
+ 
++// The automatic conversion of ordinary obejcts to smart pointers is disabled
++// for PyROOT because it can cause trouble with overload resolution. If a
++// function has overloads for both ordinary objects and smart pointers, then
++// the implicit conversion to smart pointers can result in the smart pointer
++// overload being hit, even though there would be an overload for the regular
++// object. Since PyROOT didn't have this feature before 6.32 anyway, disabling
++// it was the safest option.
++#if 0
+ // for the case where we have an ordinary object to convert
+     if (!pyobj->IsSmart() && Cppyy::IsSubtype(oisa, fUnderlyingType)) {
+     // create the relevant smart pointer and make the pyobject "smart"
+@@ -2852,6 +2860,7 @@ bool CPyCppyy::SmartPtrConverter::SetArg(
+ 
+         return true;
+     }
++#endif
+ 
+ // final option, try mapping pointer types held (TODO: do not allow for non-const ref)
+     if (pyobj->IsSmart() && Cppyy::IsSubtype(oisa, fUnderlyingType)) {
+-- 
+2.44.0
+
diff --git a/bindings/pyroot/cppyy/sync-upstream b/bindings/pyroot/cppyy/sync-upstream
index 4d9c2f18bd0d8..58a94d7cc2c14 100755
--- a/bindings/pyroot/cppyy/sync-upstream
+++ b/bindings/pyroot/cppyy/sync-upstream
@@ -49,6 +49,7 @@ git apply patches/CPyCppyy-Add-converters-and-executors-for-ROOT-types.patch
 git apply patches/CPyCppyy-TString_converter.patch
 git apply patches/CPyCppyy-Adapt-to-no-std-in-ROOT.patch
 git apply patches/CPyCppyy-Always-convert-returned-std-string.patch
+git apply patches/CPyCppyy-Disable-implicit-conversion-to-smart-ptr.patch
 git apply patches/cppyy-No-CppyyLegacy-namespace.patch
 git apply patches/cppyy-Remove-Windows-workaround.patch
 git apply patches/cppyy-Don-t-enable-cling-autoloading.patch