diff --git a/mesonbuild/compilers/compilers.py b/mesonbuild/compilers/compilers.py
index 1e86978b4..a6585543d 100644
--- a/mesonbuild/compilers/compilers.py
+++ b/mesonbuild/compilers/compilers.py
@@ -1619,7 +1619,10 @@ class PGICompiler:
             return ['-silent']
 
         def openmp_flags(self):
-            return ['-fopenmp']
+            return ['-mp']
+
+    def get_allow_undefined_link_args(self):
+        return []
 
 
 class FlangCompiler:
@@ -1639,7 +1642,10 @@ class FlangCompiler:
             return ['-silent']
 
         def openmp_flags(self):
-            return ['-fopenmp']
+            return ['-mp']
+
+    def get_allow_undefined_link_args(self):
+        return []
 
 
 class ElbrusCompiler(GnuCompiler):
diff --git a/mesonbuild/compilers/fortran.py b/mesonbuild/compilers/fortran.py
index 911df46cc..3387ddaa2 100644
--- a/mesonbuild/compilers/fortran.py
+++ b/mesonbuild/compilers/fortran.py
@@ -371,7 +371,7 @@ class PathScaleFortranCompiler(FortranCompiler):
         return ['-mp']
 
 
-class PGIFortranCompiler(FortranCompiler):
+class PGIFortranCompiler(PGICompiler, FortranCompiler):
     def __init__(self, exelist, version, is_cross, exe_wrapper=None, **kwags):
         FortranCompiler.__init__(self, exelist, version, is_cross, exe_wrapper, **kwags)
         PGICompiler.__init__(self, CompilerType.PGI_STANDARD)
@@ -383,7 +383,7 @@ class PGIFortranCompiler(FortranCompiler):
         return val
 
 
-class FlangFortranCompiler(FortranCompiler):
+class FlangFortranCompiler(FlangCompiler, FortranCompiler):
     def __init__(self, exelist, version, is_cross, exe_wrapper=None, **kwags):
         FortranCompiler.__init__(self, exelist, version, is_cross, exe_wrapper, **kwags)
         FlangCompiler.__init__(self, CompilerType.FLANG_STANDARD)