diff --git a/src/libANGLE/Framebuffer.cpp b/src/libANGLE/Framebuffer.cpp
index 398c980..0880984 100644
--- a/src/libANGLE/Framebuffer.cpp
+++ b/src/libANGLE/Framebuffer.cpp
@@ -268,7 +268,7 @@
 {
     for (size_t colorAttachment = 0; colorAttachment < mData.mColorAttachments.size(); ++colorAttachment)
     {
-        if (isEnabledColorAttachment(colorAttachment))
+        if (isEnabledColorAttachment(static_cast<unsigned int>(colorAttachment)))
         {
             return true;
         }
@@ -286,7 +286,7 @@
 {
     for (size_t colorAttachment = 1; colorAttachment < mData.mColorAttachments.size(); ++colorAttachment)
     {
-        if (isEnabledColorAttachment(colorAttachment))
+        if (isEnabledColorAttachment(static_cast<unsigned int>(colorAttachment)))
         {
             return true;
         }