diff --git a/mlir/lib/CAPI/IR/IR.cpp b/mlir/lib/CAPI/IR/IR.cpp
--- a/mlir/lib/CAPI/IR/IR.cpp
+++ b/mlir/lib/CAPI/IR/IR.cpp
@@ -183,10 +183,12 @@
 }
 
 #define APPEND_ELEMS(type, sizeName, elemName)                                 \
-  state->elemName =                                                            \
-      (type *)realloc(state->elemName, (state->sizeName + n) * sizeof(type));  \
-  memcpy(state->elemName + state->sizeName, elemName, n * sizeof(type));       \
-  state->sizeName += n;
+  if (n > 0) {                                                                 \
+    state->elemName = (type *)realloc(state->elemName,                         \
+                                      (state->sizeName + n) * sizeof(type));   \
+    memcpy(state->elemName + state->sizeName, elemName, n * sizeof(type));     \
+    state->sizeName += n;                                                      \
+  }
 
 void mlirOperationStateAddResults(MlirOperationState *state, intptr_t n,
                                   MlirType const *results) {