diff --git a/src/modules/previewpane/GcodeThumbnailProviderCpp/GcodeThumbnailProvider.cpp b/src/modules/previewpane/GcodeThumbnailProviderCpp/GcodeThumbnailProvider.cpp
index 89dcbdd986..977557d12d 100644
--- a/src/modules/previewpane/GcodeThumbnailProviderCpp/GcodeThumbnailProvider.cpp
+++ b/src/modules/previewpane/GcodeThumbnailProviderCpp/GcodeThumbnailProvider.cpp
@@ -183,6 +183,12 @@ IFACEMETHODIMP GcodeThumbnailProvider::GetThumbnail(UINT cx, HBITMAP* phbmp, WTS
         }
     }
 
+    // ensure releasing the stream (not all if branches contain it)
+    if (m_pStream)
+    {
+        m_pStream->Release();
+        m_pStream = NULL;
+    }
 
     return S_OK;
 }
diff --git a/src/modules/previewpane/PdfThumbnailProviderCpp/PdfThumbnailProvider.cpp b/src/modules/previewpane/PdfThumbnailProviderCpp/PdfThumbnailProvider.cpp
index a636715f61..97ee3ba796 100644
--- a/src/modules/previewpane/PdfThumbnailProviderCpp/PdfThumbnailProvider.cpp
+++ b/src/modules/previewpane/PdfThumbnailProviderCpp/PdfThumbnailProvider.cpp
@@ -182,6 +182,13 @@ IFACEMETHODIMP PdfThumbnailProvider::GetThumbnail(UINT cx, HBITMAP* phbmp, WTS_A
         }
     }
 
+    // ensure releasing the stream (not all if branches contain it)
+    if (m_pStream)
+    {
+        m_pStream->Release();
+        m_pStream = NULL;
+    }
+
     return S_OK;
 }
 
diff --git a/src/modules/previewpane/QoiThumbnailProviderCpp/QoiThumbnailProvider.cpp b/src/modules/previewpane/QoiThumbnailProviderCpp/QoiThumbnailProvider.cpp
index 50781f5d29..9984e6755e 100644
--- a/src/modules/previewpane/QoiThumbnailProviderCpp/QoiThumbnailProvider.cpp
+++ b/src/modules/previewpane/QoiThumbnailProviderCpp/QoiThumbnailProvider.cpp
@@ -183,6 +183,12 @@ IFACEMETHODIMP QoiThumbnailProvider::GetThumbnail(UINT cx, HBITMAP* phbmp, WTS_A
         }
     }
 
+    // ensure releasing the stream (not all if branches contain it)
+    if (m_pStream)
+    {
+        m_pStream->Release();
+        m_pStream = NULL;
+    }
 
     return S_OK;
 }
diff --git a/src/modules/previewpane/StlThumbnailProviderCpp/StlThumbnailProvider.cpp b/src/modules/previewpane/StlThumbnailProviderCpp/StlThumbnailProvider.cpp
index c06f7b9d03..bb055bea7d 100644
--- a/src/modules/previewpane/StlThumbnailProviderCpp/StlThumbnailProvider.cpp
+++ b/src/modules/previewpane/StlThumbnailProviderCpp/StlThumbnailProvider.cpp
@@ -181,6 +181,13 @@ IFACEMETHODIMP StlThumbnailProvider::GetThumbnail(UINT cx, HBITMAP* phbmp, WTS_A
         }
     }
 
+    // ensure releasing the stream (not all if branches contain it)
+    if (m_pStream)
+    {
+        m_pStream->Release();
+        m_pStream = NULL;
+    }
+
     return S_OK;
 }
 
diff --git a/src/modules/previewpane/SvgThumbnailProviderCpp/SvgThumbnailProvider.cpp b/src/modules/previewpane/SvgThumbnailProviderCpp/SvgThumbnailProvider.cpp
index 139fe99c22..5bd80e6252 100644
--- a/src/modules/previewpane/SvgThumbnailProviderCpp/SvgThumbnailProvider.cpp
+++ b/src/modules/previewpane/SvgThumbnailProviderCpp/SvgThumbnailProvider.cpp
@@ -182,6 +182,13 @@ IFACEMETHODIMP SvgThumbnailProvider::GetThumbnail(UINT cx, HBITMAP* phbmp, WTS_A
         }
     }
 
+    // ensure releasing the stream (not all if branches contain it)
+    if (m_pStream)
+    {
+        m_pStream->Release();
+        m_pStream = NULL;
+    }
+
     return S_OK;
 }