diff --git a/CMakeLists.txt b/CMakeLists.txt
index ff7a3984..ef27bc80 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -418,6 +418,12 @@ CHECK_CXX_COMPILER_FLAG("-Wunused-local-typedefs" CXX_UNUSED_LOCAL_TYPEDEFS)
 # gcc5 complains about this
 CHECK_CXX_COMPILER_FLAG("-Wunused-variable" CXX_WUNUSED_VARIABLE)
 
+# gcc 10 complains about this
+CHECK_C_COMPILER_FLAG("-Wstringop-overflow" CC_STRINGOP_OVERFLOW)
+if(CC_STRINGOP_OVERFLOW)
+    set(EXTRA_C_FLAGS "${EXTRA_C_FLAGS} -Wno-stringop-overflow")
+endif()
+
 endif()
 
 include_directories(SYSTEM ${Boost_INCLUDE_DIRS})
diff --git a/unit/internal/graph_undirected.cpp b/unit/internal/graph_undirected.cpp
index babc01a6..73d3e357 100644
--- a/unit/internal/graph_undirected.cpp
+++ b/unit/internal/graph_undirected.cpp
@@ -40,12 +40,12 @@ using namespace std;
 using namespace ue2;
 
 struct SimpleV {
-    size_t index;
+    size_t index = 0;
     string test_v = "SimpleV";
 };
 
 struct SimpleE {
-    size_t index;
+    size_t index = 0;
     string test_e = "SimpleE";
 };