diff --git a/clang/lib/StaticAnalyzer/Core/CheckerHelpers.cpp b/clang/lib/StaticAnalyzer/Core/CheckerHelpers.cpp
index 8b404377186e9..9cf31af37f116 100644
--- a/clang/lib/StaticAnalyzer/Core/CheckerHelpers.cpp
+++ b/clang/lib/StaticAnalyzer/Core/CheckerHelpers.cpp
@@ -142,19 +142,25 @@ std::optional<int> tryExpandAsInteger(StringRef Macro, const Preprocessor &PP) {
   if (InvalidSpelling)
     return std::nullopt;
 
-  llvm::APInt IntValue;
+  llvm::APSInt IntValue(0, true);
   constexpr unsigned AutoSenseRadix = 0;
-  if (ValueStr.getAsInteger(AutoSenseRadix, IntValue))
+  if (ValueStr.getAsInteger(AutoSenseRadix,
+                            static_cast<llvm::APInt &>(IntValue)))
     return std::nullopt;
 
   // Parse an optional minus sign.
   size_t Size = FilteredTokens.size();
   if (Size >= 2) {
-    if (FilteredTokens[Size - 2].is(tok::minus))
+    if (FilteredTokens[Size - 2].is(tok::minus)) {
+      // Make sure there's space for a sign bit
+      if (IntValue.isSignBitSet())
+        IntValue = IntValue.extend(IntValue.getBitWidth() + 1);
+      IntValue.setIsUnsigned(false);
       IntValue = -IntValue;
+    }
   }
 
-  return IntValue.getSExtValue();
+  return IntValue.getExtValue();
 }
 
 OperatorKind operationKindFromOverloadedOperator(OverloadedOperatorKind OOK,
diff --git a/clang/test/Analysis/std-c-library-functions-eof-2-rad.c b/clang/test/Analysis/std-c-library-functions-eof-2-rad.c
new file mode 100644
index 0000000000000..6ead28b97fbf7
--- /dev/null
+++ b/clang/test/Analysis/std-c-library-functions-eof-2-rad.c
@@ -0,0 +1,16 @@
+// RUN: %clang_analyze_cc1 -std=c23 -analyzer-checker=core,unix.StdCLibraryFunctions,debug.ExprInspection -verify -analyzer-config eagerly-assume=false %s
+
+void clang_analyzer_eval(int);
+
+typedef struct FILE FILE;
+/// Test that the static analyzer doesn't interpret the most significant bit as the sign bit.
+// Unorthodox EOF value with a power of 2 radix
+#define EOF (-0b11)
+
+int getc(FILE *);
+void test_getc(FILE *fp) {
+  int y = getc(fp);
+  if (y < 0) {
+    clang_analyzer_eval(y == EOF); // expected-warning{{TRUE}}
+  }
+}