diff --git a/clang/lib/StaticAnalyzer/Core/RegionStore.cpp b/clang/lib/StaticAnalyzer/Core/RegionStore.cpp
--- a/clang/lib/StaticAnalyzer/Core/RegionStore.cpp
+++ b/clang/lib/StaticAnalyzer/Core/RegionStore.cpp
@@ -2497,8 +2497,8 @@
     return bindAggregate(B, R, Init);
   }
 
-  if (Init.isUnknown())
-    return bindAggregate(B, R, UnknownVal());
+  if (!isa<nonloc::CompoundVal>(Init))
+    return bindAggregate(B, R, Init);
 
   // Remaining case: explicit compound values.
   const nonloc::CompoundVal& CV = Init.castAs<nonloc::CompoundVal>();
diff --git a/clang/test/Analysis/region-store.c b/clang/test/Analysis/region-store.c
--- a/clang/test/Analysis/region-store.c
+++ b/clang/test/Analysis/region-store.c
@@ -1,4 +1,6 @@
-// RUN: %clang_analyze_cc1 -analyzer-checker=core,unix,debug.ExprInspection -verify -analyzer-config eagerly-assume=false %s
+// RUN: %clang_analyze_cc1 -analyzer-checker=core,unix,debug.ExprInspection \
+// RUN:    -verify -analyzer-config eagerly-assume=false -std=c99 %s \
+// RUN:    -Wno-implicit-function-declaration
 
 int printf(const char *restrict,...);
 
@@ -54,3 +56,13 @@
     clang_analyzer_eval(values[0] == 4);// expected-warning {{UNKNOWN}}
   }
 }
+
+int buffer[10];
+void b(); // expected-warning {{a function declaration without a prototype is deprecated in all versions of C and is treated as a zero-parameter prototype in C2x, conflicting with a subsequent definition}}
+void top() {
+  // expected-warning@+1 {{passing arguments to 'b' without a prototype is deprecated in all versions of C and is not supported in C2x}}
+  b(&buffer);
+}
+void b(int *c) { // expected-note {{conflicting prototype is here}}
+  *c = 42; // no-crash
+}