diff --git a/openmp/runtime/src/kmp_settings.cpp b/openmp/runtime/src/kmp_settings.cpp
--- a/openmp/runtime/src/kmp_settings.cpp
+++ b/openmp/runtime/src/kmp_settings.cpp
@@ -3272,6 +3272,7 @@
   }
   __kmp_str_buf_print(buffer, "%s'\n", __kmp_affinity_format);
 }
+
 // OMP_ALLOCATOR sets default allocator
 static void __kmp_stg_parse_allocator(char const *name, char const *value,
                                       void *data) {
@@ -3289,104 +3290,65 @@
   */
   const char *buf = value;
   const char *next;
-  int num;
   SKIP_WS(buf);
-  if ((*buf > '0') && (*buf < '9')) {
-    next = buf;
-    SKIP_DIGITS(next);
-    num = __kmp_str_to_int(buf, *next);
-    KMP_ASSERT(num > 0);
-    switch (num) {
-    case 4:
+  next = buf;
+  // check HBW first as the only non-default supported
+  if (__kmp_match_str("omp_high_bw_mem_alloc", buf, &next) ||
+      __kmp_match_str("4", buf, &next)) {
+    SKIP_WS(next);
+    if (*next == '\0') {
       if (__kmp_memkind_available) {
         __kmp_def_allocator = omp_high_bw_mem_alloc;
+        return;
       } else {
-        __kmp_msg(kmp_ms_warning,
-                  KMP_MSG(OmpNoAllocator, "omp_high_bw_mem_alloc"),
-                  __kmp_msg_null);
-        __kmp_def_allocator = omp_default_mem_alloc;
+        KMP_WARNING(OmpNoAllocator, "omp_high_bw_mem_alloc");
       }
-      break;
-    case 1:
-      __kmp_def_allocator = omp_default_mem_alloc;
-      break;
-    case 2:
-      __kmp_msg(kmp_ms_warning,
-                KMP_MSG(OmpNoAllocator, "omp_large_cap_mem_alloc"),
-                __kmp_msg_null);
-      __kmp_def_allocator = omp_default_mem_alloc;
-      break;
-    case 3:
-      __kmp_msg(kmp_ms_warning, KMP_MSG(OmpNoAllocator, "omp_const_mem_alloc"),
-                __kmp_msg_null);
-      __kmp_def_allocator = omp_default_mem_alloc;
-      break;
-    case 5:
-      __kmp_msg(kmp_ms_warning,
-                KMP_MSG(OmpNoAllocator, "omp_low_lat_mem_alloc"),
-                __kmp_msg_null);
-      __kmp_def_allocator = omp_default_mem_alloc;
-      break;
-    case 6:
-      __kmp_msg(kmp_ms_warning, KMP_MSG(OmpNoAllocator, "omp_cgroup_mem_alloc"),
-                __kmp_msg_null);
-      __kmp_def_allocator = omp_default_mem_alloc;
-      break;
-    case 7:
-      __kmp_msg(kmp_ms_warning, KMP_MSG(OmpNoAllocator, "omp_pteam_mem_alloc"),
-                __kmp_msg_null);
-      __kmp_def_allocator = omp_default_mem_alloc;
-      break;
-    case 8:
-      __kmp_msg(kmp_ms_warning, KMP_MSG(OmpNoAllocator, "omp_thread_mem_alloc"),
-                __kmp_msg_null);
-      __kmp_def_allocator = omp_default_mem_alloc;
-      break;
     }
-    return;
-  }
-  next = buf;
-  if (__kmp_match_str("omp_high_bw_mem_alloc", buf, &next)) {
-    if (__kmp_memkind_available) {
-      __kmp_def_allocator = omp_high_bw_mem_alloc;
-    } else {
-      __kmp_msg(kmp_ms_warning,
-                KMP_MSG(OmpNoAllocator, "omp_high_bw_mem_alloc"),
-                __kmp_msg_null);
-      __kmp_def_allocator = omp_default_mem_alloc;
+  } else if (__kmp_match_str("omp_default_mem_alloc", buf, &next) ||
+             __kmp_match_str("1", buf, &next)) {
+    // default requested
+    SKIP_WS(next);
+  } else if (__kmp_match_str("omp_large_cap_mem_alloc", buf, &next) ||
+             __kmp_match_str("2", buf, &next)) {
+    SKIP_WS(next);
+    if (*next == '\0') {
+      KMP_WARNING(OmpNoAllocator, "omp_large_cap_mem_alloc");
+    }
+  } else if (__kmp_match_str("omp_const_mem_alloc", buf, &next) ||
+             __kmp_match_str("3", buf, &next)) {
+    SKIP_WS(next);
+    if (*next == '\0') {
+      KMP_WARNING(OmpNoAllocator, "omp_const_mem_alloc");
+    }
+  } else if (__kmp_match_str("omp_low_lat_mem_alloc", buf, &next) ||
+             __kmp_match_str("5", buf, &next)) {
+    SKIP_WS(next);
+    if (*next == '\0') {
+      KMP_WARNING(OmpNoAllocator, "omp_low_lat_mem_alloc");
+    }
+  } else if (__kmp_match_str("omp_cgroup_mem_alloc", buf, &next) ||
+             __kmp_match_str("6", buf, &next)) {
+    SKIP_WS(next);
+    if (*next == '\0') {
+      KMP_WARNING(OmpNoAllocator, "omp_cgroup_mem_alloc");
+    }
+  } else if (__kmp_match_str("omp_pteam_mem_alloc", buf, &next) ||
+             __kmp_match_str("7", buf, &next)) {
+    SKIP_WS(next);
+    if (*next == '\0') {
+      KMP_WARNING(OmpNoAllocator, "omp_pteam_mem_alloc");
+    }
+  } else if (__kmp_match_str("omp_thread_mem_alloc", buf, &next) ||
+             __kmp_match_str("8", buf, &next)) {
+    SKIP_WS(next);
+    if (*next == '\0') {
+      KMP_WARNING(OmpNoAllocator, "omp_thread_mem_alloc");
     }
-  } else if (__kmp_match_str("omp_default_mem_alloc", buf, &next)) {
-    __kmp_def_allocator = omp_default_mem_alloc;
-  } else if (__kmp_match_str("omp_large_cap_mem_alloc", buf, &next)) {
-    __kmp_msg(kmp_ms_warning,
-              KMP_MSG(OmpNoAllocator, "omp_large_cap_mem_alloc"),
-              __kmp_msg_null);
-    __kmp_def_allocator = omp_default_mem_alloc;
-  } else if (__kmp_match_str("omp_const_mem_alloc", buf, &next)) {
-    __kmp_msg(kmp_ms_warning, KMP_MSG(OmpNoAllocator, "omp_const_mem_alloc"),
-              __kmp_msg_null);
-    __kmp_def_allocator = omp_default_mem_alloc;
-  } else if (__kmp_match_str("omp_low_lat_mem_alloc", buf, &next)) {
-    __kmp_msg(kmp_ms_warning, KMP_MSG(OmpNoAllocator, "omp_low_lat_mem_alloc"),
-              __kmp_msg_null);
-    __kmp_def_allocator = omp_default_mem_alloc;
-  } else if (__kmp_match_str("omp_cgroup_mem_alloc", buf, &next)) {
-    __kmp_msg(kmp_ms_warning, KMP_MSG(OmpNoAllocator, "omp_cgroup_mem_alloc"),
-              __kmp_msg_null);
-    __kmp_def_allocator = omp_default_mem_alloc;
-  } else if (__kmp_match_str("omp_pteam_mem_alloc", buf, &next)) {
-    __kmp_msg(kmp_ms_warning, KMP_MSG(OmpNoAllocator, "omp_pteam_mem_alloc"),
-              __kmp_msg_null);
-    __kmp_def_allocator = omp_default_mem_alloc;
-  } else if (__kmp_match_str("omp_thread_mem_alloc", buf, &next)) {
-    __kmp_msg(kmp_ms_warning, KMP_MSG(OmpNoAllocator, "omp_thread_mem_alloc"),
-              __kmp_msg_null);
-    __kmp_def_allocator = omp_default_mem_alloc;
   }
-  buf = next;
-  SKIP_WS(buf);
-  if (*buf != '\0') {
-    KMP_WARNING(ParseExtraCharsWarn, name, buf);
+  __kmp_def_allocator = omp_default_mem_alloc;
+  if (next == buf || *next != '\0') {
+    // either no match or extra symbols present after the matched token
+    KMP_WARNING(StgInvalidValue, name, value);
   }
 }
 
diff --git a/openmp/runtime/test/env/omp_alloc_env_invalid.c b/openmp/runtime/test/env/omp_alloc_env_invalid.c
new file mode 100644
--- /dev/null
+++ b/openmp/runtime/test/env/omp_alloc_env_invalid.c
@@ -0,0 +1,16 @@
+// RUN: %libomp-compile
+// RUN: env OMP_ALLOCATOR=111 %libomp-run 2>&1 | FileCheck %s
+// RUN: env OMP_ALLOCATOR=omp_default_mem_alloc_xyz %libomp-run 2>&1 | FileCheck %s
+// UNSUPPORTED: gcc
+
+// Both invocations of the test should produce (different) warnings:
+// OMP: Warning #42: OMP_ALLOCATOR: "111" is an invalid value; ignored.
+// OMP: Warning #189: Allocator omp_const_mem_alloc is not available, will use default allocator.
+#include <stdio.h>
+#include <omp.h>
+int main() {
+  volatile int n = omp_get_max_threads(); // causes library initialization
+  return 0;
+}
+
+// CHECK: {{^OMP: Warning #[0-9]+}}: {{.*$}}